Enrichment of tungsten ores. Extraction of weakly magnetic minerals using a high-intensity magnetic separator from ores of non-ferrous, rare earth and noble metals using the example of Irgiredmet OJSC, Kovdor Mining and Processing Plant. Scheme of enrichment of tungsten clay ore

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Navoi Mining and Metallurgical Plant

Navoi State Mining Institute

"Chemical and Metallurgical" Faculty"

Department of Metallurgy

Explanatory note

for final qualifying work

on the topic of: “Selection, justification and calculation of tungsten-molybdenum ore processing technology”

Graduate: K. Sayfiddinov

Navoi-2014

• Introduction
• 1. General information about enrichment methods tungsten ores
• 2. Enrichment of molybdenum-tungsten ores
• 2. Technological section
• 2.1 Calculation of crushing scheme with equipment selection
• 2.2 Calculation of the grinding scheme
• 2.3 Selection and calculation of semi-autogenous grinding mills
• List of used literature

Introduction

Minerals are the basis National economy, and there is not a single industry where minerals or their processed products are not used.

Significant mineral reserves in many deposits of Uzbekistan make it possible to build large, highly mechanized mining, processing and metallurgical enterprises that extract and process many hundreds of millions of tons of minerals with high technical and economic indicators.

The mining industry deals with solid minerals from which, with modern technology, it is advisable to extract metals or other minerals. The main conditions for the development of mineral deposits are increasing their extraction from the subsoil and integrated use. This is due to:

- significant material and labor costs during exploration and industrial development of new deposits;

- the growing need of various sectors of the national economy for almost all mineral components that make up the ore;

- the need to create waste-free technology and thereby preventing contamination environment production waste.

For these reasons, the possibility of industrial use of a deposit is determined not only by the value and content of the mineral, its reserves, geographical location, production and transportation conditions, other economic and political factors, but also the presence of effective technology for processing mined ores.

1. General information about methods of beneficiation of tungsten ores

Tungsten ores are enriched, as a rule, in two stages - primary gravity enrichment and finishing of rough concentrates using various methods, which is explained by the low tungsten content in the processed ores (0.2 - 0.8% WO3) and high requirements for the quality of standard concentrates (55 - 65% WO3), The total enrichment degree is approximately 300 - 600.

Wolframite (huebnerite and ferberite) bedrock ores and placers usually contain a number of other heavy minerals, therefore, during the primary gravity enrichment of ores, they strive to isolate collective concentrates, which can contain from 5 to 20% WO3, as well as cassiterite, tantalite-columbite, magnetite, sulfides, etc. When finishing collective concentrates, it is necessary to obtain conditioned monomineral concentrates, for which flotation or flotogravity of sulfides, magnetic separation of magnetite in a weak magnetic field, and wolframite in a stronger one can be used. It is possible to use electric separation, gravitational enrichment on tables, flotation of gangue minerals and other processes to separate minerals so that the finished concentrates meet the requirements of GOSTs and technical specifications not only for the content of the base metal, but also for the content of harmful impurities.

Considering the high density tungsten minerals(6 - 7.5 g/cm 3), during enrichment, gravitational enrichment methods can be successfully used on jigs, concentration tables, sluices, jet and screw separators, etc. When valuable minerals are finely disseminated, flotation or a combination of gravitational processes with flotation is used. Considering the possibility of wolframite sludge during gravitational enrichment, flotation is used as an auxiliary process even when enriching coarsely disseminated wolframite ores for more complete extraction of tungsten from sludge.

If there are large tungsten-rich ore pieces or large pieces of waste rock in the ore, sorting of ore with a particle size of 150 + 50 mm on belt conveyors can be used to separate the rich large-lump concentrate or pieces of rock that dilute the ore supplied for enrichment.

When beneficiating scheelite ores, gravity is also used, but most often a combination of gravity methods with flotation and flotation gravity, or flotation alone.

When sorting scheelite ores, luminescent installations are used. Scheelitis when irradiated ultraviolet rays glows a bright blue light, allowing you to separate pieces of scheelite or pieces of gangue.

Scheelite is an easily floated mineral characterized by high sludge properties. The extraction of scheelite increases significantly with flotation enrichment compared to gravity, therefore, in the enrichment of scheelite ores in the CIS countries, flotation has now begun to be used in all factories.

During the flotation of tungsten ores, a number of difficult technological problems arise that require the right decision depending on the material composition and association of individual minerals. In the process of flotation of wolframite, hübnerite and ferberite, it is difficult to separate from them iron oxides and hydroxides, tourmaline and other minerals containing neutralize their flotation properties with tungsten minerals.

Flotation of scheelite from ores with calcium-containing minerals (calcite, fluorite, apatite, etc.) is carried out by anionic fatty acid collectors, ensuring their good flotation with calcium cations of scheelite and other calcium-containing minerals. Separation of scheelite from calcium-containing minerals is possible only with the use of such regulators as liquid glass, sodium fluorosilicone, soda, etc.

2. Enrichment of molybdenum-tungsten ores

On Tyrnyauzskaya The factory enriches the molybdenum-tungsten ores of the Tyrnyauz deposit, which are complex in the material composition of not only valuable minerals with very fine dissemination, but also associated gangue minerals. Ore minerals - scheelite (tenths of a percent), molybdenite (hundredths of a percent), powellite, partially ferrimolybdite, chalcopyrite, bismuthite, pyrrhotite, pyrite, arsenopyrite. Nonmetallic minerals - skarns (50-70%), hornfels (21-48%), granite (1 - 12%), marble (0.4-2%), quartz, fluorite, calcite, apatite (3-10%) and etc.

In the upper part of the deposit, 50-60% of molybdenum is represented by powellite and ferrimolybdite, in the lower part their content decreases to 10-20%. Molybdenum is present in scheelite as an isomorphic impurity. Part of the molybdenite, oxidized from the surface, is covered with a film of powellite. Part of the molybdenum grows very finely with molybdoscheelite.

More than 50% of oxidized molybdenum is associated with scheelite in the form of powellite inclusions - a decomposition product of the Ca(W, Mo)O 4 solid solution. Such forms of tungsten and molybdenum can only be isolated into a collective concentrate with subsequent separation by hydrometallurgical methods.

Since 1978, the ore preparation scheme at the factory has been completely reconstructed. Previously, ore, after large crushing at the mine, was transported to the factory in trolleys via an overhead cableway. In the crushing department of the factory, the ore was crushed to - 12 mm, unloaded into bunkers and then crushed in one stage in ball mills operating in a closed cycle with double-spiral classifiers, up to 60% of the class - 0.074 mm.

A new ore preparation technology was developed jointly by the Mekhanobr Institute and the plant and put into operation in August 1978.

The ore preparation scheme provides for coarse crushing of the original ore up to -350 mm, screening according to the 74 mm class, separate storage of each class in bunkers for the purpose of more precise regulation feeding large and small classes of ore into the autogenous grinding mill.

Self-grinding of coarse ore (-350 mm) is carried out in Cascade type mills with a diameter of 7 m (MMC-70X X23) with additional grinding of the coarse-grained fraction to 62% class -0.074 mm in MSHR-3600X5000 mills operating in a closed cycle with single-spiral classifiers 1KSN-3 and located in a new building on the mountainside at an elevation of about 2000 m above sea level between the mine and the operating factory.

Innings finished product from the autogenous vessel to flotation is carried out by hydraulic transport. The hydraulic transport route is a unique engineering structure that ensures the transportation of pulp with a height difference of more than 600 m. It consists of two pipelines with a diameter of 630 mm, a length of 1750 m, equipped with stilling wells with a diameter of 1620 mm and a height of 5 m (126 wells for each pipeline).

The use of a hydraulic transport system made it possible to eliminate the cargo workshop cable cars, medium and fine crushing building, MSHR-3200X2100 mills at the processing plant. In the main building of the factory, two main flotation sections, new scheelite and molybdenum finishing departments, a liquid glass melting shop, and recycling water supply systems were built and put into operation. The thickening front for rough flotation concentrates and middlings has been significantly expanded due to the installation of thickeners with a diameter of 30 m, which reduces losses from thickening discharges.

The newly commissioned facilities are equipped with modern automated process control systems and local automation systems. Thus, in the autogenous building the automatic control system operates in direct control mode based on M-6000 computers. In the main building, a system for centralized control of the material composition of the pulp was introduced using X-ray spectral analyzers KRF-17 and KRF-18 in combination with an M-6000 computer. An automated system for sampling and delivery of samples (by pneumatic mail) to the express laboratory, controlled by the KM-2101 computer complex and issuing analyzes by teletype, has been mastered.

One of the most complex processing processes - finishing rough scheelite concentrates according to the method of N. S. Petrov - is equipped with an automatic monitoring and control system, which can work either in the “advisor” mode to the flotation operator, or in the mode of direct control of the process, regulating the flow rate of the suppressor (liquid glass), pulp level in cleaning operations and other process parameters.

The sulfide minerals flotation cycle is equipped with automatic control and dosing systems for collector (butyl xanthate) and suppressor (sodium sulfide) in the copper-molybdenum flotation cycle. The systems operate using ion-selective electrodes as sensors.

Due to the increase in production volume, the factory switched to processing new varieties of ores, characterized by a lower content of certain metals and a higher degree of oxidation. This required improvement of the reagent regime for flotation of sulfide-oxidized ores. In particular, a progressive technological solution was used in the sulfide cycle - a combination of two foaming agents of active and selective types. Reagents containing terpene alcohols are used as an active foaming agent, and a new reagent LV, developed for the enrichment of multicomponent ores, primarily Tyrnyauz ores, is used as a selective agent.

In the flotation cycle of oxidized minerals by fatty acid collectors, intensifying additives of a modifier reagent based on low molecular weight carboxylic acids are used. To improve the flotation properties of circulating industrial products pulp, regulation of their ionic composition has been introduced. Methods of chemical finishing of concentrates have found wider application.

From the autogenous grinding mill, the ore is sent to screening. Class +4 mm is further ground in a ball mill. Mill overflow and under-screen product (--4 mm) are subject to I and II classifications.

690 g/t soda and 5 g/t transformer oil are fed into the ball mill. The classifier discharge goes to the main molybdenum flotation, where 0.5 g/t xanthate and 46 g/t terpineol are fed. After I and II cleaning flotations, the molybdenum concentrate (1.2-1.5% Mo) is subjected to steaming with liquid glass (12 g/t) at 50-70°C, III cleaning flotation and further grinding to 95-98% class --0.074 mm with a supply of 3 g/t sodium cyanide and 6 g/t liquid glass.

The finished molybdenum concentrate contains about 48% Mo, 0.1% Cu and 0.5% WO 3 with a Mo extraction of 50%. The control flotation tailings of the III and IV cleaning operations are thickened and sent to copper-molybdenum flotation with a supply of 0.2 g/t xanthate and 2 g/t kerosene. The twice purified copper-molybdenum concentrate, after steaming with sodium sulfide, is sent to selective flotation, where a copper concentrate containing 8-10% Cu (with an extraction of about 45%), 0.2% Mo, 0.8% Bi is isolated.

The tailings of the control molybdenum flotation, containing up to 0 2% WO 3, are sent to scheelite flotation, carried out through a very branched and complex scheme. After mixing with liquid glass (350 g/t), basic scheelite flotation is carried out with sodium oleate (40 g/t). After the first cleaning flotation and thickening to 60% solid, the scheelite concentrate is steamed with liquid glass (1600 g/t) at 80--90 °C. Next, the concentrate is cleaned twice more and again goes to steaming at 90--95 ° C with liquid glass (280 g/t) and is cleaned again three times.

2. Technological section

2.1 Calculation of crushing scheme with equipment selection

The designed concentration plant is intended for processing molybdenum-containing tungsten ores.

Medium-sized ore (f = 12 ± 14 units on Professor Protodyakonov’s scale) is characterized by a density c = 2.7 t/m 3 and is supplied to the factory with a moisture content of 1.5%. Maximum piece d=1000 mm.

In terms of productivity, the enrichment plant belongs to the category of medium productivity (Table 4/2/), according to the international classification - to group C.

To the factory ore D max. =1000 mm is supplied from open-pit mining.

1. Let's determine the productivity of the coarse crushing shop. We calculate productivity according to Razumov K.A. 1, pp. 39-40. The project adopted the delivery of ore 259 days a year, in 2 shifts of 7 hours, 5 days a week.

Ore strength factor /2/

where: Q c. etc. - daily productivity of the crushing shop, t/day

Coefficient taking into account the uneven properties of raw materials /2/

where: Q h..t. dr - hourly productivity of the crushing shop, t/h

k n - coefficient taking into account the uneven properties of raw materials,

n days - estimated number of working days per year,

n cm - number of shifts per day,

t cm - shift duration,

k" - coefficient for accounting for ore strength,

Calculation of annual working hours:

C = (n day n cm t cm) = 259 2 5 = 2590 (3)

Time utilization rate:

k in = 2590/8760 = 0.29 units = 29%

2. Calculation of crushing scheme. We carry out the calculation according to pp. 68-78 2.

According to the instructions, the moisture content of the initial ore is 1.5%, i.e. e.

Calculation procedure:

1. Determine the degree of fragmentation

2. Let us accept the degree of fragmentation.

3. Let’s determine the maximum size of products after crushing:

4. Let's determine the width of the crusher's discharge slots, taking the typical characteristics Z - coarsening of the crushed product relative to the size of the discharge slot.

5. Let’s check the compliance of the selected crushing scheme with the manufactured equipment.

The requirements that crushers must satisfy are listed in Table 1.

Table 1

In terms of the width of the receiving opening and the range of adjustment of the discharge slot, crushers of the ShchDP 12X15 brand are suitable.

Let's calculate the productivity of the crusher using the formula (109/2/):

Q cat. = m 3 / h

Q fraction. = Q cat. · with n · k f · k cr. · k ow. · k c, m 3 / h (7)

where c n is the bulk density of ore = 1.6 t/m 3,

Q cat. - passport capacity of the crusher, m 3 / h

k f . , k ow. , kcr, kc - correction factors for strength (crushingability), bulk density, ore size and moisture content.

The value of the coefficients is found from the table k f =1.6; k cr =1.05; k ow. =1%;

Q cat. = S pr. / S n · Q n = 125 / 155 · 310 ? 250 m 3 /h

Let's find the actual productivity of the crusher for the conditions defined by the project:

Q fraction. = 250 · 1.6 · 1.00 · 1.05 · 1 · 1 = 420 t/h

Based on the calculation results, we determine the number of crushers:

We accept 12 x 15 boards for installation - 1 pc.

2.2 Calculation of the grinding scheme

The grinding scheme chosen in the project is a type of VA Razumov K.A. page 86.

Calculation procedure:

1. Determining the hourly productivity of the grinding shop , which is actually the hourly productivity of the entire factory, since the grinding shop is the main ore preparation building:

where 343 is the number of working days in a year

24 - continuous work week 3 shifts of 8 hours (3x8=24 hours)

Kv - equipment utilization factor

Kn - coefficient taking into account the uneven properties of raw materials

We accept: K in =0.9 K n =1.0

The coarse ore warehouse provides a two-day supply of ore:

V= 48,127.89 / 2.7 = 2398.22

We accept the initial data

Let's ask ourselves about liquefaction in plums and sands classification:

R 10 =3 R 11 =0.28

(R 13 is based on row 2 p. 262 depending on the size of the drain)

in 1 -0.074 =10% - class content - 0.074 mm in crushed ore

in 10 -0.074 =80% - class content - 0.074 mm in the classification plum.

We accept the optimal circulation load With opt = 200%.

Calculation procedure:

Grinding stages I and II are represented by a type VA scheme, page 86 fig. 23.

Calculation of scheme B comes down to determining the weights of products 2 and 5 (product yields are found according to general formula g n = Q n: Q 1)

Q 7 = Q 1 C opt = 134.9 · 2 = 269.8 t/h;

Q 4 = Q 5 = Q 3 + Q 7 = 404.7 t/h;

g 4 = g 5 = 300%;

g 3 = g 6 = 100%

The calculation is carried out according to Razumov K.A. 1 pp. 107-108.

1. Calculation of scheme A

Q 8 = Q 10 ; Q 11 = Q 12 ;

Q 9 = Q 8 + Q 12 = 134.88 + 89.26 = 224.14 t/h

g 1 = 100%; g 8 = g 10 = 99.987%;

g 11 = g 12 =Q 12: Q 1 = 89.26: 134.88 = 66.2%;

g 9 = Q 9: Q 1 = 224.14: 134.88 = 166.17%

Process flow diagramschleniyamolybdenum-tungsten ores.

CalculationByqualitative-quantitative scheme.

Initial data for calculating qualitative-quantitative schemess.

Extraction of tungsten into the final concentrate - e tungsten 17 = 68%

Extraction of tungsten into collective concentrate - e tungsten 15 =86%

Extraction of tungsten into molybdenum concentrate - e tungsten 21 = 4%

Extraction of molybdenum into the final concentrate - e Mo 21 = 77%

Extraction of molybdenum into tungsten flotation tailings - e Mo 18 =98%

Extraction of molybdenum into control flotation concentrate - eMo 19 =18%

Extraction of molybdenum into collective concentrate - e Mo 15 = 104%

Yield of collective concentrate - g 15 = 36%

Yield of tungsten concentrate - g 17 = 14%

Yield of molybdenum concentrate - g 21 = 15%

Yield of control flotation concentrate - g 19 =28%

Determining the yield of enrichment products

G 18 = g 15 - G 17 =36-14=22%

G 22 = g 18 - G 21 =22-15=7%

G 14 = g 13 + g 19 + g 22 =100+28+7=135%

G 16 = g 14 - G 15 =135-36=99%

G 20 = g 16 - G 19 =99-28=71%

Determining the masses of enrichment products

Q 13 = 127.89t/h.

Q 1 4 = Q 13 XG 14 = 127.89x1.35=172.6 t/h

Q 1 5 = Q 13 XG 15 = 127.89x0.36=46.0 t/h

Q 1 6 = Q 13 XG 16 = 127.89x0.99=126.6t/h

Q 1 7 = Q 13 XG 17 = 127.89x0.14=17.9 t/h

Q 1 8 = Q 13 XG 18 = 127.89x0.22=28.1 t/h

Q 1 9 = Q 13 XG 19 = 127.89x0.28=35.8 t/h

Q 20 = Q 13 XG 20 = 127.89x0.71=90.8 t/h

Q 21 = Q 13 XG 21 = 127.89x0.15=19.1 t/h

Q 22 = Q 13 XG 22 = 127.89x0.07=8.9 t/h

Determining the recovery of enrichment products

For tungsten

e tungsten 13 =100 %

e tungsten 18 = e tungsten 15 - e tungsten 17 =86-68=28 %

e tungsten 22 = e tungsten 18 - e tungsten 21 =28-14=14 %

e tungsten 14 = e tungsten 13 + e tungsten 22 + e tungsten 19 =100+14+10=124 %

e tungsten 16 = e tungsten 14 - e tungsten 15 =124-86=38%

e tungsten 20 = e tungsten 13 - e tungsten 17 + e tungsten 21 =100 - 68+4=28%

e tungsten 19 = e tungsten 16 - e tungsten 20 =38-28=10 %

for molybdenum

e Mo 13 =100%

e Mo 22 = e Mo 18 - e Mo 21 =98-77=11 %

e Mo 14 = e Mo 13 + e Mo 22 + e Mo 19 =100+11+18=129 %

e Mo 16 = e Mo 14 - e Mo 15 =129-94=35 %

e Mo 17 = e Mo 15 - e Mo 18 =104-98=6%

e Mo 20 = e Mo 13 - e Mo 17 + e Mo 21 =100 - 6+77=17%

e Mo 19 = e Mo 16 - e Mo 20 =35-17=18%

Determining the amount of metals in the product Oh enrichment

For tungsten

14 =124 x0.5 / 135=0.46%

15 =86x0.5 / 36=1.19%

16 =38 x0.5 / 99=0.19%

17 =68 x0.5 / 14=2.43%

18 =28 x0.5 / 22=0.64%

19 =10 x0.5 / 28=0.18%

20 =28 x0.5 / 71=0.2%

21 =14 x0.5 / 15=0.46%

22 =14 x0.5 / 7=1%

For molybdenum

14 =129 x0.04/ 135=0.04%

15 =94x0.04/ 36=0.1%

16 =35 x0.04 / 99=0.01%

17 =6 x0.04 / 14=0.017%

18 =98 x0.04 / 22=0.18%

19 =18 x0.04 / 28=0.025%

20 =17 x0.04 / 71=0.009%

21 =77 x0.04 / 15=0.2%

22 =11 x0.04 / 7=0.06%

Table 3. Table of qualitative-quantitative enrichment scheme

Operation no. cont.		Q, t/h	, %	copper , %	copper , %	zinc , %	zinc , %
I	Grinding stage I
	arrives
	crushed ore
	comes out
	crushed ore
II	Classification
	arrives
	CrushedbChennsth product IArt. grinding
	CrushedbChennsth product II st .grinding
	comes out
	drain
	sands
III	Grinding I I stage
	arrives
	Sands classification
	comes out
	Shreddedsth product
IV	Collective Wo 3 -Mo flotation
	arrives
	Drain classification
	TailsMo flotationAnd
	comes out
	concentrate
	tails
V	Control flotation
	arrives
	Tailcollective flotation
	comes out
	concentrate
	tails
VI	Tungsten flotation
	arrives
	Concentratecollective flotation
	comes out
	concentrate
	tails
	Mo flotation
	arrives
	Tails Wo 3 flotation
	comes out
	concentrate
	tails

Calculation of water-sludge scheme .

The purpose of calculating the water-sludge scheme is to: ensure optimal liquid: solid ratios in the operations of the scheme; determining the amount of water added to operations or, conversely, released from products during dehydration operations; determination of L:T ratios in the products of the scheme; determination of the total water requirement and specific water consumption per ton of processed ore.

To get high technological indicators ore processing every operation technological scheme must be carried out at optimal values ​​of the F:T ratio. These values ​​are established based on data from ore dressing tests and the operating practices of existing processing plants.

The relatively low specific water consumption per ton of processed ore is explained by the presence of intra-factory water circulation at the designed plant, since the thickener drains are fed into the grinding - classification cycle. Water consumption for flushing floors, washing equipment and for other purposes is 10-15% of the total consumption.

Table 3. Table of qualitative-quantitative enrichment scheme.

Opera no.walkie-talkies cont.	Name of operations and products	Q, t/h	, %	R	W
I	Grinding stage I
	arrives
	crushed ore			0 , 0 25
	comes out
	crushed ore
II	Classification
	arrives
	CrushedbChennsth product IArt. grinding
	CrushedbChennsth product II st .grinding
	comes out
	drain
	sands
III	Grinding I I stage
	arrives
	Sands classification
	comes out
	Shreddedsth product
IV	Collective Wo 3 -Mo flotation
	arrives
	Drain classification
	Control flotation concentrate
	Tails Mo flotationAnd
	comes out
	concentrate
	Tails
V	Control flotation
	arrives
	Tailcollective flotation
	comes out
	concentrate
	Tails
VI	Tungsten flotation
	Incoming
	Concentratecollective flotation
	It turns out
	Concentrate
	Tails
	Mo flotation
	Incoming
	Tails tungstenflotation
	It turns out
	concentrate
	tails

Crusher selection and calculation.

The choice of crusher type and size depends on physical properties ore, required crusher capacity, crushed product size and ore hardness.

Tungsten-molybdenum ore by strength category is an ore of medium strength.

The maximum size of a piece of ore entering the crushing operation is 1000 mm.

To crush the ore coming from the mine, I install a jaw crusher with a simple swing jaw ShchDP 12x15. *

Crusher productivity, Q is equal to:

Q =q*L*i, t/h,

where q - specific productivity of the jaw crusher per 1 cm 2 of the discharge slot area, t/(cm 2 * h);

L is the length of the discharge slot of the neck crusher, cm;

i - width of the unloading slot, see /4/

According to the experience of the crushing department processing plant The specific productivity of the jaw crusher is 0.13 t/cm2 * hour.

The productivity of a jaw crusher will be determined by:

Q= 0.13*150*15.5 = 302.25 t/h.

The crusher accepted for installation provides the specified ore productivity.

The maximum size of a piece in the crusher feed will be:

120*0.8 = 96 cm.

Selection and calculation of grate screen

A grate screen with a hole size of 95 cm (950 mm) is installed in front of the crusher.

The required screening area is determined by the formula:

where Q* - productivity, t/h;

a is a coefficient equal to the width of the gap between the grates, mm. /5/ According to the layout conditions, the width of the grate screen is taken to be 2.7 m, length 4.5 m.

The practice of the crushing department of the factory shows that the ore delivered from the quarry contains about 4.5% of pieces with a particle size of more than 950 mm. Pieces of this size are delivered by a front-end loader to the ore yard, where they are crushed and again fed by the loader to the grate screen.

2.3 Selection and calculation of semi-autogenous grinding mills

IN Lately during processing gold ores In world and domestic practice, in the first stage of grinding, semi-autogenous grinding mills with subsequent cyanidation are becoming increasingly common. In this case, the loss of gold from iron scrap and crumbs is eliminated, the consumption of cyanide during cyanidation is reduced, and the sanitary conditions of working on quartz silicate ores are improved. Therefore, I accept a semi-autogenous grinding (SAG) mill for installation in the first stage of grinding.

1. Find the specific productivity for the newly formed class of the operating SSI mill, t/(m 3 * h):

where Q is the productivity of the operating mill, t/h;

- class content -0.074 mm in the mill discharge, %;

- class content -0.074 mm in the original product,%;

D is the diameter of the operating mill, m;

L is the length of the operating mill, m.

2. We determine the specific productivity of the designed mill according to the newly formed class:

where q 1 is the specific productivity of a working mill in the same class;

K and is a coefficient that takes into account differences in the grindability of the ore designed for processing and the ore being processed (Ki = 1);

K k - coefficient taking into account the difference in the size of the initial and final grinding products at the existing and designed factories (K k = 1);

K D is a coefficient that takes into account the difference in the diameters of the drums of the designed and operating mills:

K D = ,

where D and D 1 respectively, the nominal diameters of the drums of the mills being designed for installation and those in operation. (K D =1.1);

Kt is a coefficient that takes into account differences in the type of designed and operating mills (Kt=1).

q = 0.77*1*1*1.1*1 =0.85 t/(m 3 * h).

I accept for installation an autogenous grinding mill "Cascade" with a diameter of 7 m and a length of 2.3 m with a working volume of 81.05 m3

3. We determine the productivity of the mills for ore using the formula:

where V is the working volume of the mill. /4/

4. Determine the estimated number of mills:

n- 101/125.72 = 0.8;

then the accepted one will be equal to 1. The Cascade mill provides the specified productivity.

Screen selection and calculation II screening stage .

Draining of semi-autogenous mills using pumps...

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course work, added 11/19/2013


Geological characteristics of the deposit. Characteristics of the processed ore, development and calculation of its crushing scheme. Selection and calculation of equipment for the crushing department. Determination of the number of shifts and labor costs to provide crushing technology.

course work, added 02/25/2012


Technology of enrichment of iron ore and concentrate, analysis of the experience of foreign enterprises. Characteristics of the mineral composition of the ore, requirements for the quality of the concentrate. Technological calculation of water-sludge and qualitative-quantitative enrichment scheme.

course work, added 10/23/2011


Construction of a qualitative and quantitative scheme of preparatory operations for crushing and screening of iron ore: choice of method, product yield. Review of recommended equipment. Magnetic-gravity technology and flotation concentration of iron ore.

course work, added 01/09/2012


Features and stages of crushing technology implementation. Refined calculation of the screening scheme. Selection and calculation of crushers. Determining the need for equipment for ore preparation, auxiliary equipment. Safety regulations in the crushing shop.

course work, added 01/12/2015


Selection and calculation of the main technological equipment for the processing of mineral raw materials, feeders. Calculation of screening operations. Selection and justification of the quantity of capital equipment, their specifications, purpose and main functions.

The chemical element is tungsten.

Before describing the production of tungsten, it is necessary to take a short excursion into history. The name of this metal is translated from German as “wolf’s cream”; the origin of the term goes back to the late Middle Ages.

When obtaining tin from various ores, it was noticed that in some cases it was lost, turning into foamy slag, “like a wolf devouring its prey.”

The metaphor caught on, giving the name to the later received metal; it is currently used in many languages ​​of the world. But in English, French and some other languages, tungsten is called differently, from the metaphor “heavy stone” (tungsten in Swedish). The Swedish origin of the word is associated with the experiments of the famous Swedish chemist Scheele, who first obtained tungsten oxide from the ore later named after him (scheelite).

Swedish chemist Scheele, who discovered tungsten.

Industrial production of tungsten metal can be divided into 3 stages:

• ore beneficiation and production of tungsten anhydrite;
• reduction to powder metal;
• obtaining monolithic metal.

Ore beneficiation

Tungsten does not occur in a free state in nature; it is present only in various compounds.

• wolframites
• scheelites

These ores often contain small quantities of other substances (gold, silver, tin, mercury, etc.), despite the very low content of additional minerals, sometimes their associated extraction during enrichment is economically feasible.

1. Beneficiation begins with crushing and grinding the rock. The material is then sent for further processing, the methods of which depend on the type of ore. Enrichment of wolframite ores is usually carried out using the gravitational method, the essence of which is to use the combined forces of gravity and centrifugal force; minerals are separated according to chemical and physical properties - density, particle size, wettability. This way, the waste rock is separated, and the concentrate is brought to the required purity using magnetic separation. The wolframite content in the resulting concentrate ranges from 52 to 85%.
2. Scheelite, unlike wolframite, is not magnetic mineral, therefore magnetic separation is not applied to it. For scheelite ores, the enrichment algorithm is different. The main method is flotation (the process of separating particles in an aqueous suspension) followed by the use of electrostatic separation. The concentration of scheelite at the outlet can be up to 90%. Ores can also be complex, containing wolframites and scheelites at the same time. To enrich them, methods combining gravitational and flotation schemes are used.
   
   If further purification of the concentrate to established standards is necessary, various procedures are used depending on the type of impurities. To reduce phosphorus impurities, scheelite concentrates are processed in the cold hydrochloric acid, at the same time calcite and dolomite are removed. To remove copper, arsenic, and bismuth, roasting followed by treatment with acids is used. There are other cleaning methods.

Several different methods are used to convert tungsten from a concentrate into a soluble compound.

1. For example, the concentrate is sintered with an excess of soda, thus obtaining sodium wolframite.
2. Another method can be used - leaching: tungsten is extracted soda solution under pressure at high temperature, followed by neutralization and precipitation.
3. Another method is to treat the concentrate with chlorine gas. This process produces tungsten chloride, which is then separated from the chlorides of other metals by sublimation. The resulting product can be converted into tungsten oxide or processed directly into elemental metal.

The main result of various enrichment methods is the production of tungsten trioxide. Further, it is he who goes into the production of metal tungsten. Tungsten carbide is also obtained from it, which is the main component of many hard alloys. There is another product of direct processing of tungsten ore concentrates - ferrotungsten. It is usually smelted for the needs of ferrous metallurgy.

Tungsten Recovery

The resulting tungsten trioxide (tungsten anhydrite) must be reduced to the metal state in the next step. Reduction is most often carried out using the widely used hydrogen method. A moving container (boat) with tungsten trioxide is fed into the furnace, the temperature rises as it moves, hydrogen is supplied towards it. As the metal is restored, the bulk density of the material increases, the loading volume of the container decreases by more than half, so in practice it is run in 2 stages, through different types of furnaces.

1. At the first stage, dioxide is formed from tungsten trioxide, at the second, pure tungsten powder is obtained from the dioxide.
2. Then the powder is sifted through a mesh, and large particles are additionally ground to obtain a powder with a given grain size.

Carbon is sometimes used to reduce tungsten. This method simplifies production somewhat, but requires higher temperatures. In addition, coal and the impurities it contains react with tungsten, forming various compounds that lead to contamination of the metal. There are a number of other methods used in production around the world, but in terms of all parameters, hydrogen reduction has the highest applicability.

Obtaining monolithic metal

If the first two stages industrial production Since tungsten is well known to metallurgists and has been used for a very long time, obtaining a monolith from powder required the development of a special technology. Most metals are obtained by simple melting and then cast into molds; with tungsten, due to its main property - refractoriness - such a procedure is impossible. The method of producing compact tungsten from powder, proposed at the beginning of the 20th century by the American Coolidge, is still used with various variations in our time. The essence of the method is that the powder turns into a monolithic metal under the influence of electric current. Instead of conventional smelting, several steps must be taken to obtain tungsten metal. At the first of them, the powder is pressed into special bars. Then these posts are subjected to a sintering procedure, and this is done in two stages:

1. 1. First, at temperatures up to 1300ºC, the rod is pre-sintered to increase its strength. The procedure is carried out in a special sealed oven with a continuous supply of hydrogen. Hydrogen is used for additional reduction; it penetrates into the porous structure of the material, and with additional exposure to high temperature, a purely metallic contact is created between the crystals of the sintered rod. After this stage, the headstock is significantly strengthened, losing up to 5% in size.
   2. Then proceed to the main stage - welding. This process is carried out at temperatures up to 3 thousandºC. The post is secured with clamping contacts, and an electric current is passed through it. Hydrogen is also used at this stage - it is needed to prevent oxidation. The current used is very high; for bars with a cross-section of 10x10 mm, a current of about 2500 A is required, and for a cross-section of 25x25 mm - about 9000 A. The voltage used is relatively small, from 10 to 20 V. For each batch of monolithic metal, a test bar is first welded, it is used to calibrate the welding mode. The duration of welding depends on the size of the post and usually ranges from 15 minutes to an hour. This stage, like the first, also leads to a reduction in the size of the stack.

The density and grain size of the resulting metal depend on the initial grain size of the rod and the maximum welding temperature. The loss of dimensions after two stages of sintering is up to 18% along the length. The final density is 17–18.5 g/cm².

To obtain highly purified tungsten, various additives are used that evaporate during the welding process, for example, silicon oxides and alkali metals. As they heat up, these additives evaporate, taking other impurities with them. This process promotes additional cleaning. When using the correct temperature conditions and the absence of traces of moisture in a hydrogen atmosphere during sintering with the help of such additives, the degree of tungsten purification can be increased to 99.995%.

Production of tungsten products

Obtained from the original ore after the three production stages described, monolithic tungsten has a unique set of properties. In addition to refractoriness, it is characterized by very high stability of geometric dimensions, preservation of strength at high temperatures and the absence of internal stress. Tungsten also has good ductility and malleability. Further production most often involves drawing out wire. These are technologically relatively simple processes.

1. The blanks enter a rotary forging machine, where the material is compressed.
2. Then the drawing method produces wire of various diameters (drawing is drawing a rod using special equipment through tapering holes). This way you can obtain the thinnest tungsten wire with a total degree of deformation of 99.9995%, while its strength can reach 600 kg/mm².

Tungsten began to be used for filaments electric lamps even before the development of a method for producing malleable tungsten. The Russian scientist Lodygin, who had previously patented the principle of using a filament for a lamp, in the 1890s proposed using tungsten wire twisted into a spiral as such a filament. How did you get tungsten for such wires? First, a mixture of tungsten powder with some kind of plasticizer (for example, paraffin) was prepared, then a thin thread was pressed out of this mixture through a hole of a given diameter, dried and calcined in hydrogen. The result was a rather fragile wire, straight sections of which were attached to the electrodes of the lamp. There were attempts to obtain compact metal using other methods, however, in all cases, the fragility of the threads remained critically high. After the work of Coolidge and Fink, the production of tungsten wire gained a solid technological basis, and the industrial use of tungsten began to grow rapidly.

An incandescent lamp invented by the Russian scientist Lodygin.

World tungsten market

Tungsten production volumes are about 50 thousand tons per year. The leader in production, as well as in consumption, is China; this country produces approximately 41 thousand tons per year (Russia, for comparison, produces 3.5 thousand tons). An important factor currently is the processing of secondary raw materials, usually scrap tungsten carbide, shavings, sawdust and tungsten powder residues; such processing provides about 30% of global tungsten consumption.

Filaments from burnt-out incandescent lamps are practically not recycled.

The global tungsten market has recently shown a decline in demand for tungsten filaments. This is due to the development of alternative technologies in the field of lighting - fluorescent and LED bulbs aggressively replace conventional incandescent lamps both in everyday life and in industry. According to experts, the use of tungsten in this sector will decrease by 5% per year in the coming years. The demand for tungsten as a whole is not decreasing; the decline in applicability in one sector is compensated by growth in others, including innovative industries.

Tungsten minerals and ores

Of the tungsten minerals, the minerals of the wolframite and scheelite group are of practical importance.

Wolframite (xFeWO4 yMnWO4) is an isomorphic mixture of iron and manganese tungstates. If a mineral contains more than 80% iron, the mineral is called ferberite. If the mineral contains more than 80% manganese, then the mineral is called hubernite.

Scheelite CaWO4 is almost pure calcium tungstate.

Tungsten ores contain small amounts of tungsten. The minimum WO3 content at which their processing is advisable. is 0.14-0.15% for large deposits and 0.4-0.5% for small deposits. In ores, tungsten is accompanied by tin in the form of cassiterite, as well as the minerals molybdenum, bismuth, arsenic and copper. The main gangue rock is silica.

Tungsten ores undergo beneficiation. Wolframite ores are enriched using the gravity method, and scheelite ores are enriched by flotation.

Tungsten ore enrichment schemes are varied and complex. They combine gravitational enrichment with magnetic separation, flotation gravity and flotation. By combining various enrichment methods, concentrates containing up to 55-72% WO3 are obtained from ores. The extraction of tungsten from ore into concentrate is 82-90%.

Composition tungsten concentrates fluctuates within the following limits,%: WO3-40-72; MnO-0.008-18; SiO2-5-10; Mo-0.008-0.25; S-0.5-4; Sn-0.03-1.5; As-0.01-0.05; P-0.01-0.11; Cu-0.1-0.22.

Technological schemes for processing tungsten concentrates are divided into two groups: alkaline and acidic.

Methods for processing tungsten concentrates

Regardless of the method of processing wolframite and scheelite concentrates, the first stage of their processing is opening, which is the transformation of tungsten minerals into easily soluble chemical compounds.

Wolframite concentrates are opened by sintering or fusion with soda at a temperature of 800-900°C, which is based on chemical reactions:

4FeWO4 + 4Na2CO3 + O2 = 4Na2WO4 + 2Fe2O3 +4CO2 (1)

6MnWO4 + 6Na2CO3 + O2 = 6Na2WO4 + 2Mn3O4 +6CO2 (2)

When sintering scheelite concentrates at a temperature of 800-900°C, the following reactions occur:

CaWO4 + Na2CO3 = Na2WO4+ CaCO3 (3)

CaWO4 + Na2CO3 = Na2WO4+ CaO + CO2 (4)

In order to reduce soda consumption and prevent the formation of free calcium oxide, silica is added to the charge to bind calcium oxide into a sparingly soluble silicate:

2CaWO4 + 2Na2CO3 + SiO2 = 2Na2WO4+ Ca2SiO4 + CO2 (5)

Sintering of scheelite concentrate with soda and silica is carried out in drum furnaces at a temperature of 850-900°C.

The resulting cake (alloy) is leached with water. During leaching, sodium tungstate Na2WO4 and soluble impurities (Na2SiO3, Na2HPO4, Na2AsO4, Na2MoO4, Na2SO4) and excess soda pass into the solution. Leaching is carried out at a temperature of 80-90°C in steel reactors with mechanical stirring, operating in batch mode, or in continuous drum rotary kilns. The recovery of tungsten into the solution is 98-99%. The solution after leaching contains 150-200 g/l WO3. The solution is filtered, and after separating the solid residue, it is sent for purification from silicon, arsenic, phosphorus and molybdenum.

Purification from silicon is based on the hydrolytic decomposition of Na2SiO3 by boiling a solution neutralized at pH = 8-9. Neutralization of excess soda in the solution is carried out with hydrochloric acid. As a result of hydrolysis, slightly soluble silicic acid is formed:

Na2SiO3 + 2H2O = 2NaOH + H2SiO3 (6)

To remove phosphorus and arsenic, the method of precipitation of phosphate and arsenate ions in the form of poorly soluble ammonium-magnesium salts is used:

Na2HPO4 + MgCl2+ NH4OH = Mg(NH4)PO4 + 2NaCl + H2O (7)

Na2HAsO4 + MgCl2+ NH4OH = Mg(NH4)AsO4 + 2NaCl + H2O (8)

Purification from molybdenum is based on the decomposition of molybdenum sulfosalt, which is formed when sodium sulfide is added to a solution of sodium tungstate:

Na2MoO4 + 4NaHS = Na2MoS4 + 4NaOH (9)

Upon subsequent acidification of the solution to pH = 2.5-3.0, the sulfosalt is destroyed with the release of slightly soluble molybdenum trisulfide:

Na2MoS4 + 2HCl = MoS3 + 2NaCl + H2S (10)

Calcium tungstate is first precipitated from a purified solution of sodium tungstate using CaCl2:

Na2WO4 + CaCl2 = CaWO4 + 2NaCl. (eleven)

The reaction is carried out in a boiling solution containing 0.3-0.5% alkali

while stirring with a mechanical stirrer. The washed sediment of calcium tungstate in the form of a pulp or paste is subjected to decomposition with hydrochloric acid:

CaWO4 + 2HCl = H2WO4 + CaCl2 (12)

During decomposition, the high acidity of the pulp is maintained at about 90-120 g/l HCl, which ensures the separation of impurities of phosphorus, arsenic and partly molybdenum, which are soluble in hydrochloric acid, from the tungstic acid sediment.

Tungstic acid can also be obtained from a purified solution of sodium tungstate by direct precipitation with hydrochloric acid. When the solution is acidified with hydrochloric acid, H2WO4 precipitates as a result of hydrolysis of sodium tungstate:

Na2WO4 + 2H2O = 2NaOH + H2WO4 (11)

The alkali formed as a result of the hydrolysis reaction reacts with hydrochloric acid:

2NaOH + 2HCl = 2NaCl + 2H2O (12)

The addition of reactions (8.11) and (8.12) gives the total reaction of precipitation of tungstic acid with hydrochloric acid:

Na2WO4 + 2HCl = 2NaCl + H2WO4 (13)

However, in this case, great difficulties arise in washing the sediment from sodium ions. Therefore, at present, the latter method of tungstic acid deposition is used very rarely.

The technical tungstic acid obtained by precipitation contains impurities and therefore needs to be purified.

The most widely used method is the ammonia method for purifying technical tungsten acid. It is based on the fact that tungstic acid is highly soluble in ammonia solutions, while a significant part of the impurities it contains are insoluble in ammonia solutions:

H2WO4 + 2NH4OH = (NH4)2WO4 + 2H2O (14)

Ammonia solutions of tungstic acid may contain impurities of molybdenum and alkali metal salts.

Deeper cleaning is achieved by isolating large crystals of ammonium paratungstate from the ammonia solution, which are obtained by evaporating the solution:

12(NH4)2WO4 = (NH4)10W12O41 5H2O + 14NH3 + 2H2O (15)

tungsten acid anhydride precipitation

Deeper crystallization is impractical to avoid contamination of the crystals with impurities. From the mother liquor, enriched with impurities, tungsten is precipitated in the form of CaWO4 or H2WO4 and returned to the previous stages.

Paratungstate crystals are squeezed out on filters, then in a centrifuge, washed cold water and dry.

Tungsten oxide WO3 is obtained by calcining tungstic acid or paratungstate in a rotating tubular furnace with a stainless steel pipe and heated by electricity at a temperature of 500-850oC:

H2WO4 = WO3 + H2O (16)

(NH4)10W12O41 5H2O = 12WO3 + 10NH3 +10H2O (17)

In tungsten trioxide intended for the production of tungsten, the WO3 content must be no lower than 99.95%, and for the production of hard alloys - no lower than 99.9%

Tungsten is the most refractory metal, melting point 3380°C. And this determines its scope. It is also impossible to build electronics without tungsten; even the filament in a light bulb is tungsten.

And, naturally, the properties of the metal also determine the difficulties in obtaining it...

First, you need to find ore. These are just two minerals - scheelite (calcium tungstate CaWO 4) and wolframite (iron and manganese tungstate - FeWO 4 or MnWO 4). The latter has been known since the 16th century under the name "wolf's foam" - "Spuma lupi" in Latin, or "Wolf Rahm" in German. This mineral accompanies tin ores and interferes with the smelting of tin, turning it into slag. Therefore, it is possible to find it already in antiquity. Rich tungsten ores usually contain 0.2 - 2% tungsten. Tungsten was actually discovered in 1781.

However, this is the easiest thing to find in tungsten mining.
Next, the ore needs to be enriched. There are a bunch of methods and they are all quite complex. First of all, of course. Then - magnetic separation (if we have wolframite with iron tungstate). Next is gravitational separation, because the metal is very heavy and the ore can be washed, much like when mining gold. Nowadays they still use electrostatic separation, but it is unlikely that the method will be useful to the endangered person.

So, we have separated the ore from the gangue. If we have scheelite (CaWO 4), then we can skip the next step, but if we have wolframite, then we need to turn it into scheelite. To do this, tungsten is extracted with a soda solution under pressure and at elevated temperatures (the process takes place in an autoclave), followed by neutralization and precipitation in the form of artificial scheelite, i.e. calcium tungstate.
It is also possible to sinter wolframite with an excess of soda, then we obtain tungstate not of calcium, but of sodium, which for our purposes is not so significant (4FeWO 4 + 4Na 2 CO 3 + O 2 = 4Na 2 WO 4 + 2Fe 2 O 3 + 4CO 2).

The next two stages are leaching with water CaWO 4 -> H 2 WO 4 and decomposition with hot acid.
You can take different acids - hydrochloric (Na 2 WO 4 + 2HCl = H 2 WO 4 + 2NaCl) or nitric.
As a result, tungsten acid is isolated. The latter is calcined or dissolved in an aqueous solution of NH 3, from which paratungstate is crystallized by evaporation.
As a result, it is possible to obtain the main raw material for the production of tungsten - WO 3 trioxide with good purity.

Of course, there is also a method for producing WO 3 using chlorides, when tungsten concentrate is treated with chlorine at elevated temperatures, but this method will not be simple for the outsider.

Tungsten oxides can be used in metallurgy as an alloying additive.

So, we have tungsten trioxide and there is only one step left - reduction to metal.
There are two methods here - reduction with hydrogen and reduction with carbon. In the second case, the coal and the impurities it always contains react with tungsten, forming carbides and other compounds. Therefore, tungsten comes out “dirty”, brittle, and for electronics it is pure that is very desirable, because having only 0.1% iron, tungsten becomes brittle and it is impossible to draw the thinnest wire for incandescent filaments from it.
The coal process also has one more drawback - high temperature: 1300 – 1400°C.

However, production with hydrogen reduction is also not a gift.
The reduction process takes place in special tube furnaces, heated in such a way that as it moves through the tube, the “boat” of WO3 passes through several temperature zones. A stream of dry hydrogen comes towards it. Recovery occurs in both “cold” (450...600°C) and “hot” (750...1100°C) zones; in “cold” ones – to the lower oxide WO 2, then – to the elemental metal. Depending on the temperature and duration of the reaction in the “hot” zone, the purity and grain size of the powdered tungsten released on the walls of the “boat” change.

So, we have obtained pure tungsten metal in the form of a tiny powder.
But this is not yet an ingot of metal from which something can be made. The metal is produced by powder metallurgy. That is, it is first pressed, sintered in a hydrogen atmosphere at a temperature of 1200-1300 °C, then an electric current is passed through it. The metal is heated to 3000 °C, and sintering occurs into a monolithic material.

However, we rather need not ingots or even rods, but thin tungsten wire.
As you yourself understand, here again everything is not so simple.
Wire drawing is carried out at a temperature of 1000°C at the beginning of the process and 400-600°C at the end. In this case, not only the wire, but also the die is heated. Heating is carried out by a gas burner flame or an electric heater.
In this case, after drawing, the tungsten wire is coated with graphite lubricant. The surface of the wire must be cleaned. Cleaning is carried out using annealing, chemical or electrolytic etching, and electrolytic polishing.

As you can see, the task of producing a simple tungsten filament is not as simple as it seems. And only the basic methods are described here; there are probably a lot of pitfalls there.
And, of course, even now tungsten is not a cheap metal. Now one kilogram of tungsten costs more than $50, the same molybdenum is almost two times cheaper.

Actually, there are several uses for tungsten.
Of course, the main ones are radio and electrical engineering, where tungsten wire goes.

The next one is the production of alloy steels, which are distinguished by their particular hardness, elasticity and strength. Added together with chromium to iron, it produces so-called high-speed steels, which retain their hardness and sharpness even when heated. They are used to make cutters, drills, milling cutters, as well as other cutting and drilling tools (in general, drilling tools contain a lot of tungsten).
Tungsten-rhenium alloys are interesting - they are used to make high-temperature thermocouples that operate at temperatures above 2000°C, although only in an inert environment.

Well, and one more thing interesting application- These are tungsten welding electrodes for electric welding. Such electrodes are non-consumable and it is necessary to supply additional metal wire to the welding site to provide a weld pool. Tungsten electrodes are used in argon arc welding - for welding non-ferrous metals such as molybdenum, titanium, nickel, as well as high-alloy steels.

As you can see, tungsten production is not for ancient times.
And why is tungsten there?
Tungsten can only be obtained with the construction of electrical engineering - with the help of electrical engineering and for electrical engineering.
No electricity means no tungsten, but you don’t need it either.