JPS58193341A - Preparation of silicon or ferrosilicon - Google Patents

Abstract

PURPOSE:To prepare pure silicon or ferrosilicon with high silicon concn. in a shaft furnace, by dissolving silicon formed by reacting a silicic acid stock material, a carbonaceous stock material and a combustion support gas in the shaft furnace in a tin type molten metal to precipitate and separate the same. CONSTITUTION:A silica rock stock material such as silica rock and a carbonaceous stock material are crushed and bonded to prepare a briquet. This briquet and, according to necessity, auxiliary fuel are charged into a shaft furnace 1 while a combustion support gas containing oxygen in high concn. is blown into the furnace 1 from a tuyere 4 provided to the furnace bed part thereof to form a high temp. combustion part. In the next step molten tin or a molten alloy based on tin and lead is flowed down from the upper part of the tuyere 4 to dissolve silicon formed in the upper part of the furnace 1 in the molten metal. The resulting molten metal is taken out of the furnace 1 to be cooled and silicon or ferrosilicon is precipitated and separated from the molten metal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has not been previously made. The present invention relates to a method for producing pure silicon or silicon-concentrated ferrosilicon in a shaft furnace using high-temperature combustion heat of carbonaceous fuel such as coal or coke.

According to conventional reports on the production of ferrosilicon using a shaft furnace, it is said that products containing 30% or less silicon can be produced, but there have been no reports on products containing more than 30% silicon. 30%
The above-mentioned silicon-containing ferrosilicon and pure silicon have been produced using silica stone (anhydrous silicic acid S i 02 ) as a carbonaceous reducing material using coke and coal in an electric furnace.
JIS containing 75-80% silicon, the most commonly used
It is known that standard No. 2 ferrosilicon and pure silicon have some difficulties even in electric furnaces. This is because silicon monoxide (SiO) and silicon carbide (SiC) are intermediately generated during the reaction process. SiO gasifies and if a blow-through occurs inside the furnace, a large amount of heat is carried out from inside the furnace, resulting in a loss of heat.

It also forms hard particles inside the furnace, which obstructs uniform ventilation within the furnace. If SiC is not quickly consumed in the furnace, it gradually turns into a non-reactive solid substance and impedes smooth reactions within the furnace.

Current electric furnaces operate while controlling these problems, but the aforementioned 7Erosilicon No. 2 product, or silicon, requires a large amount of electricity to manufacture, and the pure silicon (V) 10,000 to 14,000 kwh of power is required. This is fatal in areas where electricity costs are high. Therefore, the present inventor conducted research on a method for producing silicon by intuitive reduction.

He believed that the only way to avoid using electricity was to use the shaft furnace method, which uses coke and coal as heat sources.

As is well known, in a steelmaking blast furnace, iron ore is mixed with coke, which is solid carbon, and charged into a shaft furnace. Air is sent from the bottom of the furnace, and the heat of combustion from the oxygen in the coke is used to melt the iron ore into the furnace. It is reduced with carbon monoxide and carbon to form iron, and then melted at high temperatures to form molten pig iron. Carbon can reduce all metal elements as long as the temperature is high, but theoretically, by analogy with a steelmaking blast furnace, it is possible to increase the concentration by increasing the preheating temperature of the air and adding oxygen to the air. It should be possible to reduce even such active elements.

However, silicon has the aforementioned SiO and 5iCO problems.

When coarse-grained silica stone is charged into a shaft furnace together with coarse-grained coke, as is done in silicon or ferrosilicon electric furnaces, and a combustion supporting gas such as pure oxygen, which can be generated at a sufficiently high temperature, is fed. Considering this, in the solid phase, the reaction between silica stone and coke is difficult to occur, and silica in the liquid phase is viscous, so it does not react easily, and the conclusion is that silica stone only serves as a melting furnace for silica stone. Probably. During this time, SiC will gradually form and will eventually block the furnace.

Therefore, it is thought that the simple 7-yaft furnace method will not work.

Based on these considerations, the present inventor injected various sintering support gases into the silicon (Si) or Si
o. SiC is produced, and the product described in 11 above is injected as silicon into a molten metal containing tin or tin and lead as the main components (hereinafter all referred to as molten tin alloy), and tin containing this silicon is formed. This problem was solved by separating the silicon by taking the molten alloy out of the furnace and cooling it outside the furnace. At this time, if iron is included in the raw material, ferrosilicon can be separated from the molten tin alloy instead of silicon.

In the invention, combustion support gas with a high oxygen concentration is blown into the tuyeres in the lower part of the furnace to burn the carbon. Therefore, the charged carbon content is used for reducing silicon etc.
Some things burn and become a heat source. At the tuyere, fuel combustion takes priority in the presence of oxygen, so reduced silicon and the like are easily reoxidized. In order to prevent this, it is desirable to be able to distinguish between the fuel and the reducing agent. Also S
If a large amount of iO is volatilized, a lump will be formed in the upper part of the furnace. S
r Oi'1 At high temperatures, it reacts with carbon (C) and SiC,
Generates SiC and St. From this point of view, SiO is generated internally.

The structure is such that the raw material S i 02 is trapped by carbon before it escapes to the outside, and the briquette has a multi-layered structure in which the raw material S i 02 is sealed inside with the necessary amount of reducing carbon, and a layer of carbon for combustion is created on the outside. This was found to be preferable for this purpose. Furthermore, when there is a shortage of fuel.

It has been found that if fine-grained coke is used instead of this briquette, good results can be obtained because the coke burns preferentially. Moreover, if a large amount of molten tin alloy is circulated to the produced silicon, the reaction can be carried out smoothly even with a simple briquette, so the above method is a preferable method, but is not an essential condition.

Various fuels and reducing agents can be considered.

It is best to use coal and coke since they are large in quantity. Further, as described above, fine coke may be simply supplied as auxiliary fuel.

Fine particles of coal or coke are used as the reducing material, or the outer layer of multilayer briquette is used as the fuel. This is other carbonaceous raw material 1
This does not mean that petroleum coke, charcoal, etc. are completely eliminated.

The details of the test will be explained below, including the method for producing the main raw material, briquette.

Manufacture four types of briquettes as shown in Figure 1.1. Ta. ] is a homogeneous mixture, and 244 is a multilayer structure. The coal used was a mixture of several types of coking coal, with a volatile content of 26.5% after mixing.

Fixed carbon was 65.1%. The briquette method used a tablet press. After mixing about 5% caking agent in each case, I
For K, tablets of 40 mmφX 5 Q mm were made using a tablet press. For 2 and 3, make small diameter tablets using another tablet press in advance, then 4QmmφX 50m, m
The outer layer was coated with coal using a tablet press.

In addition to the briquette machine mentioned above, two types of equipment were prepared to conduct this test. The - are coking ovens and the others are shaft ovens implementing the invention.

In the 41J-forming furnace, tablets formed in a shaft furnace are charged from the upper part of the furnace, and fuel and combustion air are introduced from the middle or lower part of the furnace for combustion.
The fuel is heated and dry distilled to about 0.000"C and turned into coke and gas. The top gas of this coking furnace and the top gas of a reduction shaft furnace can be used as fuel, but they may also be prepared separately. It is also possible to supply gas to the furnace; such coking ovens are well known and will not be described in detail.

Table 1: Mixing example (weight ratio with silica powder as 1) The shaft furnace for reducing silicic anhydride used to carry out the present invention is a shaft furnace that performs melting similar to a blast furnace for steelmaking, as shown in the figure. One difference is that the molten tin alloy is preferably sprayed from the top of the furnace or the upper part of the tuyere. In the figure, the coked briquette fired in the coking furnace described above and coke as an auxiliary fuel are mixed and fed from the upper part of the shaft furnace. A combustion supporting gas containing high concentration of oxygen (02)k is fed into the furnace from the middle through all the tuyeres 4, and the coke and the coke portion of the briquette are combusted to maintain the combustion zone 2 at a high temperature. This high temperature reduces silicic anhydride with carbon, resulting in S
i, Sac, and Sac7 are all dissolved in the tin alloy as silicon.

The reaction during this time is complicated, but in 9 typical examples, 1:l''S
iO and SiC il), +21. It is thought to occur in the reaction of f3) and become 81 in the reactions of f4) and f51.

5iOz+ C= SiO+ Co・・・・・・・・・
・・・・・・・・・(1) SiO+2C-=SiC+Co
・・・・・・・・・ ・・・ (2) SiC+2sto2
= 3SiO+ Co・・・・・・・・・・(3) 2S
iO=Si+5iOz・・・・・・・・・・・・・
...(4) SiO-1-8iO=2Sj + Co
--f5i Thus, S i 02 is SiO and Si
Finally, Si becomes Si through C and is dissolved in tin.

A gas whose main component is CO is generated from the top of the furnace.

This gas is cooled by the -H waste heat boiler 7, part of the gas is removed with dust by the dust remover 8, moisture is removed by the dehumidifier 9, and the inert gas or Use as combustion gas. The molten tin alloy containing silicon is put into the eluator 6, and when cooled, pure silicon or, if iron is included in the raw material, ferrosilico/ is precipitated first. After this is removed, the tin alloy whose temperature has dropped is returned to the shaft furnace.

The entire system in the diagram is based on the actual 7 steno system, but 1. All briquette reduction tests were carried out using test equipment consisting of tub and tube production equipment, coking shaft furnace, reduction shaft furnace, top gas purification equipment, and eluator. As a tin alloy, pure tin is used, and from the furnace 20 to 40% of the number of atoms is
Extract an alloy containing silicon with a weight ratio of 5.6" to 13.6%.The alloy discharged from the furnace (.
-1700'C, but if the temperature is lowered to 800°C or lower using an eluator, most of the nickel will precipitate, so this molten tin is further cooled and circulated using a pump.

In this way, the above-mentioned four types of 2-play plates with an inner diameter of approximately 0.
Table 2 shows an example of the results of processing in a shaft furnace with a length of 8 m and a Q of approximately 4.5 nL. .

It was blown into the tuyere at the bottom of the shaft furnace. In either case, the furnace produces about 88% CO2, about 6% H2, and 3% CO2 N2.
3% exhaust gas is generated at a rate of approximately 6 o'7h.

Table 2 In Table 2, the coked briquette is 4Qmmφx s o
The coke was prepared by coking raw tablets of 1.5 mm in size, and the coke used was one passed through a 25 mm sieve F, 1 own sieve.

The fuel ratio is the amount of carbon required per unit weight of silica stone reduced to silicon. Therefore, multiplying this number by 60/28=2 gives the required amount of carbon per silicon obtained.

The molten metal is soo~75o1 from the top of the furnace at 500~600℃
Spray at a rate of %. The obtained high-temperature silicon-tin alloy is placed in a cylindrical refractory container (eluator) and a water-cooled metal rod is inserted into the center while centrifugally rotating, and highly pure silicon is precipitated. This silicon is crushed if necessary, washed with molten lead, and the molten lead-tin is completely separated using a centrifuge. The purity of the product is about 97% St, and the main impurities are iron and titanium derived from coal.The separated molten tin is circulated in a shaft furnace.

Looking at Table 2, all of them are producing silicon with satisfactory results. When looked at in detail, the silicon yield and fuel ratio of the double-layer briquette are superior to that of a single briquette. Looking further, it seems that the carbon content in the inner layer further controls the performance, but this difference will not be discussed here.

The silicon production rate, silicon yield, fuel ratio, etc. of tazo mono-briquette 1 are considerably higher than those of 2.3.4, and here we will only say that multi-layer is preferable. However, since I is also economically viable, it falls within the scope of the present invention.

On the other hand, for comparison, silica blocks were charged together with all the coke for reduction, but we were able to operate with a fuel ratio twice as high as in Table 2.
There were 11 cases with unstable operating conditions with many open holes, and it was judged that it could not be put to practical use.

Now, in addition to the conditions shown, there are some points to keep in mind when carrying out this method based on various experiments, which will be explained below.

As mentioned above, the product purity is 97%, which is particularly unfavorable for aluminum alloys and the like. In order to increase the purity, silicon is precipitated in two stages, and when the residual molten metal reaches about 1250°C, the cooling rod is pulled out and another cooling rod is inserted. What was thus deposited on the first half of the cooling rod was silicon with a high purity of about 99%. The latter half of the cooling ends when the residual molten metal reaches a temperature of 1000° C. or less. As mentioned earlier, tin is a good molten metal for extracting silicon, but tin is an extremely expensive metal. Therefore, it may be possible to dilute tin using a third metal, metal. A typical example is lead with a weight/l ratio of 4.
It can be used without any particular problem up to about 0. If the temperature is higher than this, it becomes necessary to gradually raise the temperature of the lower part of the furnace, resulting in unstable operation with many blow-throughs.

Although the exact limit for the amount of lead in lead-tin alloys is unclear, it is clear that pure lead is not acceptable. When pure lead is used, the temperature in the lower part of the furnace is close to the boiling point of lead, and only a small amount of silicon can be melted at this temperature. Substitutes for lead include blue lead and anti-seven. Copper can be used for dilution in small amounts. Therefore, it is unthinkable to mix tin or tin-lead alloy with a small amount of antimony and copper, which are cheaper than tin.
Ru.

Furthermore, during actual use, as mentioned above, it is inevitable that iron and titanium will be mixed in as unavoidable impurities from raw materials.

In the following text, all tin-based alloys are rotated as molten metal to take advantage of handling advantages, but tin and lead have a small latent heat of solidification, so they are first solidified and made into granules.

It is also possible to place it in a shaft furnace together with the raw material charge. Although the method of supplying it in solid form is slightly disadvantageous, it is technically exactly the same.

Since tin is expensive, in order to prevent tin from escaping outside the system, the slag and dust collector dust that are generated in small quantities along with the molten metal are collected in their entirety and re-charged to the furnace as briquette raw material, or they are collected in a small electric furnace. The tin is completely recovered through reduction.

A more proactive approach is to use tin smelting slag to increase the amount of tin in the system.

The method of the present invention does not produce slag in the example described above, similar to the electric furnace method for ferrosilicon. However, a method of creating slag is also considered. In this case, lime raw material is used as an auxiliary raw material,
Mainly uses quicklime.

Although the addition of lime requires a considerable increase in the reaction temperature, the slag has a low melting point and is considerably easier to operate in the furnace, albeit with some loss of silica stone.

This slag making method is applied to utilize tin slag.

Slag generated from tin smelting, the so-called waste slag, contains silica, alumina, and lime, iron, and tin added as slag-forming materials. Its components are, for example, Sn 3%, 5i
0238%, CaO25%, Al2O38%, Fe
It is something like 017%. Sn in this slag
By using , SiO2, Cab, and FeO, Sn can be recovered while producing ferrosilicon. An example of this is shown below.

The combustion-supporting gas may include air, which may be enriched with oxygen, or may be preheated to produce hot air. However, in the above-mentioned test, it became clear that if the nitrogen concentration was increased with air instead of pure oxygen, the gas temperature at the top of the furnace would rise, blow-by would increase, and it would be necessary to use a large amount of coke.

For the four conditions of oxygen concentration of 100%, 70%, 50%, and 35%, the furnace top was Table 3 shows the test results for gas temperature and fuel ratio.

↑ As can be seen from the table, when producing pure silicon, when the cumulative concentration becomes 70- or less, the furnace top temperature rises suddenly and the fuel ratio increases. However, operation is possible up to 50%, regardless of the top gas temperature and fuel ratio. However, if the temperature is lower than this, both the top gas temperature and the fuel ratio will rise even more rapidly, making operation impossible. On the other hand, when producing JI No. 82 ferrosilicon using tin oxide, both the top gas temperature and fuel ratio rise slowly up to 50%, but below this, they rise rapidly.

Therefore, it is necessary to set the oxygen concentration to 50% or more. Preheating a gas containing 50% or more oxygen is difficult from a safety standpoint. Preheating is possible below this.

For example, 35% oxygen means that half of the oxygen supplied to the furnace is pure oxygen and the other half is supplied from air. Therefore, we preheated only the air to soo"c and supplied it from a separate tuyere from the oxygen. In this case, there was a clear improvement, but the results were not better than with 50% oxygen. Even if the air was preheated to 800°C, operation was not possible.This shows that oxygen concentration is the dominant condition.

However, 50% or more oxygen is a condition under which the present invention can be carried out, so it is clear that in practice a high concentration of oxygen should be adopted after careful consideration of economical conditions. Normally, 90% or more oxygen can be easily produced, and in the cryogenic separation method, the cost in this vicinity is the lowest.

If data is also referred to, 70% or more is preferable, and from a technical and economic point of view, 90% or more is particularly preferable. However, if pure oxygen is used, the temperature near the tuyere may become abnormally high. In such a case, the COt-based gas can be used for cooling by diluting it with air or recovering it from the furnace top gas as shown in Figure 9. These may be supplied from the same tuyere, or may be supplied from different openings of the same tuyere, or may be supplied from separate tuyeres. In these cases, care should be taken to keep the oxygen level at 50 g or more during steady operation, even including the cooling gas. Contrary to common sense, CO gas is not the fuel in this case. This is because it has the same -component as the furnace top gas.

It's just a coolant.

In that sense, the chemical composition of the fuel is nco + mH2 (1≧n, m≧0.” n0m=
1) Anything higher in C and lower in O than any composition is a fuel in this method. An attempt was made to completely destroy the coke, which is the solid fuel, from the upper part of the furnace and then supply all of the fuel, such as pulverized coal, from the tuyere, but this had a limited effect in small quantities, but in large quantities, for example, several cracks of coke It has been found that replacing the furnace with a gas is disadvantageous because it causes the temperature of the furnace top gas to rise. Therefore, although injecting fuel through tuyeres is a partial improvement technique, its use in large quantities is not recommended.

As the briquetting method, a single tablair machine (tablet press) was used in the test example, but either the briquette or pellet method can be used. All of these methods can also be applied to the production of multi-layered briquettes.

In addition, the test example showed a method in which briquette gold is once coked and then used in a shaft furnace for reduction. In a shaft furnace, since the load is applied, it is preferable to use coke to increase the strength. However, with care, multilayer briquettes that have only been dried after shaping can also be directly charged into a shaft furnace for reduction. In this case, coke will be formed in the upper part of the reduction shaft furnace. At this time, all the pyrolysis gas will be generated and the amount of gas generated in the reduction furnace will increase, so the reduction shaft furnace will reduce the processing rate per unit area. If the circulation rate of combustion support gas is reduced, it is necessary to take measures such as using refined furnace top gas in the upper part of the shaft furnace to prevent sudden and drastic temperature rises in the briquette. Also, since tar is included in the furnace top gas, there are advantages and disadvantages to omitting one step, such as the ability to produce refined gas and complication, but there are many disadvantages. However, this method also belongs to the invention.

Typical examples are listed below.

Example 1. This is a small variation of the example in Table 2.

Silica stone powder 1 was mixed with coal powder, 0.621 asphalt emulsion, and lignin as a caking agent while being calorized.

t − f 3 ], 5 mm φ x 35 mm tufflet wall. This gold was coated with coal powder mixed with the same binder.

The tablet throat is 40mmφ×50wn. This highly satisfies the blending ratio in Table 1. This tufflet was dry distilled in a coking oven as shown in Figure 1 to make coke and sewage. The coked tablets are extracted from the coking oven, cooled once, and then fed to the shaft furnace for reduction. In the shaft furnace for reduction, coking tablets are placed in 424.
25 In 20% lead 80% tin alloy 750 at about 550° C.
/h is supplied from above the furnace. Pure oxygen is supplied from the bottom of the furnace at a rate of 200 Nyyi'/i4. Gas at a temperature of about 330°C was generated from the top of the furnace, but all of this was collected and its flow rate and components were measured. CO approx. 88%.

Exhaust gas is about 6% N2, 3% N23% CO2
Occurs at a rate of ON. From the lower part of the furnace, molten tin-lead alloy containing 8.5% Si at about 1700"C is heated at 9/h.
flows out. This is placed in a cylindrical refractory container, a chrome-plated water-cooled steel rod is placed in the center, and the container is cooled while being centrifugally rotated to obtain a cylindrical silicon inborator.

When the temperature of the tin bath water falls below 1.000"C, the cooling rod is pulled north and the work is completed. The obtained silicon is crushed into appropriate sizes and placed in an iron cylindrical cage under an inert gas atmosphere.
Immerse in molten lead at °C. The entire lifted cage is placed in a centrifuge to remove lead. The silicon purity obtained when silicon precipitation from a tin-lead alloy melt is carried out in one step is about 97%.

Example 2 Coked tablets are obtained in the same manner as in Example.

Coked tablet 389 Nvh, same fine coke as in Example 1 70 kl/h, Sn 3%, 5i02
38%, CaO25%.

Tin 138k with A1203B% and Fe017% composition
Vhft furnace and 550℃ molten metal e5oo1w
, < Spray from above the furnace. Approximately 290℃ from the top of the furnace Example 1
A gas having the same composition as y is generated at a ratio of about 570 Ni,4. Si 9.8% at 1700℃ from the lower part of the furnace
, outside the tin alloy containing 3.1% Fe, about 576, and 5i
A slag of 1.80 kVh containing 0253%, CaO 35%, and Al 20al1% was produced. From this tin alloy, ferrosilicon 74"CVh containing 8176% is obtained as in Example 1-5. Furthermore, it is purified with molten lead in the same manner as in Example 1 to obtain a product equivalent to JIS No. ferrosilicon. However, since the finished product is significantly segregated, it is preferable to remelt it in an electric furnace and rapidly cool it for use in deoxidizing steel.

In both testimonials, Si is 8.5% to % by weight in the alloy.
.

The experiment was carried out at an atomic ratio of about 25 to 30%, but operation is easy if the atomic ratio is 40% or less. If the concentration is lowered, the furnace top temperature will be lowered, but if it is lowered too much, tin will be lost and the coke ratio will increase slightly. From these points of view, it is preferable to operate at an atomic ratio of 15 or more. Furthermore, it is easier to increase the Si concentration when slag is formed. Generally speaking, without slag, the upper limit should be expected to be 5-15% lower. It is possible to operate under pure tin slag up to 30% in terms of atomic ratio of 65% and 9% by weight, but if it exceeds this, the hanging of the open ceiling 9 will become severe and operation will become difficult.

So far, we have described a small-scale pilot plant experiment, but the case where this is used as a large-scale facility will be explained using a separate diagram.

The diagram is divided into several parts. Reference numerals 1 to 5 are the reduction shaft furnace main body, 7 to 10 are top gas purification systems, and 6 is a silicon separator. 11~] 4 is the briquette equipment 15 to 20 are coking shaft furnaces, 23 to 26 are top gas heat recovery systems, and 28 to 31 are exhaust gas cleaning systems. 27
is an oxygen generator. Among these, the reduction shaft furnace, furnace top gas cleaning device, silicon separator, briquette equipment, and coking shaft furnace have been mostly explained so far.

The same applies to large equipment.

In the method of the present invention, dry distillation gas of 9 coals and almost C
A top gas of O is generated and its effective utilization extends the advantages of the method of the invention. A preferred method is to purify at least the top gas by a total amount of 7 to 10, and use it as CO as a raw material for C1 chemistry. However, this cannot necessarily be expected. A common method is to recover heat by burning gas and generating electricity. In the figure, reference numeral 23 denotes a combustion chamber, into which the reduction shaft furnace top gas and coking furnace cracked gas are supplied. In the combustion chamber these gases are passed through combustion air blower 2
The combustion air supplied from 4 is used for combustion, and the heat is recovered as steam in the boiler 25, and the resulting electric power is used by the oxygen generator 27 and the proar in the system, pump 10, +9.
24.30.36 and other necessary power supplies tend to be more than enough. Now, the exhaust gas exiting the boiler 25 is removed by a dust remover 28, purified if necessary by an exhaust gas desulfurization device 29, drawn by an induced draft fan 30, and dissipated from a chimney 31.

The oxygen generator 26 may be either a cryogenic separator or a molecular sieve, but generally a cryogenic separator is preferable since nitrogen may be required within the system.

Since flammable gas flows throughout the system, it is used as a safety prevention material, and in the early stages when reducing gas is not generated, it is introduced from the valve 34 as a cooling gas instead of the refining furnace top gas to cool the coking furnace. Can be used.

As I will repeat, the loss of tin from this system greatly affects the cost, so the dust D from the gas cooler 7,
It is necessary to completely recover tin compounds from the dust E from the dust remover 28 and the slag F from the reduction shaft furnace.

Specifically, it is possible to return the dust to the pellet raw material or to reduce it together with the slag in an electric furnace. In addition, containers used for handling molten tin are washed with molten lead to recover the tin, as described in the handling of finished silicon.

When silicon It' is manufactured by the method of Example 1 using this apparatus, various basic units are calculated as follows.

2190kg of silica stone and 4370kfi coal were supplied as tablets, and 750g of fine coke was used to produce silicon lt.
get money 2400 Q 000 k from the above-mentioned furnace top gas
The calorific value of IQOOαOOOOkcal is obtained by subtracting the calorific value of cal and the calorific value used for coke dry distillation from the coking oven.

This is generated at normal efficiency to obtain 13,800 kwh of power, but the power consumption within the system is about 3,300 kwh. Note that the loss of tin per 1 silicon is 2 to 4. Surplus electricity will be used in other alloy manufacturing furnaces within the plant.

Although economic comparisons cannot be made accurately due to fluctuations, silicon can be produced much more cheaply than conventional electric furnace methods. Less, /! -Compared to the conventional electric furnace method, which required a large amount of electricity, this method is completely unprecedented in that it provides a means to directly produce silicon and silicon alloys from only coal and some coke. It is.

There are almost no documents available for producing 30% or more silicon or silicon alloys in a shaft furnace without using electric power as in the present invention. Although the method of the present invention does not directly take out silicon from the furnace, it uses a shaft furnace as the main process and contains silicon with a content of 50% or more, especially 70%.
The method of the present invention is characterized in that it is difficult to apply the method of the present invention when the purpose is to produce ferrosilicon or silicon with a silicon content of less than 10%. This is an iron pot alloy.

This is because it becomes difficult to separate only ferrosilicon. Although the present invention is extremely new, in tin refining, tin is separated using a ferrosilicon bath in an electric furnace. However, unlike the method of the present invention, this method is not connected to shaft furnace technology, so although it may serve as a reference for the present invention, it has little relevance.

As stated in each section, the present invention is complex and requires many modification means in each step. Therefore, I will list them again.

(1) The method described in the claims, characterized in that the briquette subjected to high-temperature dry distillation in a coking furnace and coked is supplied to a shaft furnace for reduction.

(2) Preferable shift is 70% or more, most preferably 90%
A method as claimed in the claims, characterized in that a combustion support gas containing one or more oxygens is used.

(3) Bulquette production equipment, shaft furnace for reduction, top gas purification equipment, boiler and generator, alR element generator.

An apparatus for carrying out the method of the claims, comprising at least an elution device.

(4) Claims using a composite briquette containing mainly silicic acid anhydride in the inner layer and coal in the outer layer or +11 above
+21 method.

(5) The method described in the claims, in which lime is blended to form calcium aluminosilicate slag and a reduction shaft furnace is operated.

(6) A claim characterized in that ferrosilicon is produced by compensating for the loss of tin in the system by utilizing waste entanglement in tin refining, and at the same time forming a calcium minosilicate-based slag. The method described.

(7) A method according to the claims, characterized in that a molten metal containing 65% or less St, preferably 15 to 40 atoms, is produced in a shaft furnace.

(8) The method described in the claims, characterized in that the silicon-containing tin-based alloy produced in a reduction shaft furnace is cooled while centrifugally rotating to elute silicon.

(9) A method in which silicon is precipitated in two stages and separated into high-purity silicon and low-purity silicon as described in (8) above.

[Brief explanation of drawings]

The figure shows 70 sheets of an actual plant. 1...........Shaft furnace for reduction 2..
... Combustion zone 3 ...... Outlet spout 4.18...
...Blade D 5 5... Hot water reservoir 6... Eluator 7... Cooler 8...・Dust remover 9...Dehumidifier 10...Proa.

Claims (1)

[Claims] The briquette produced by crushing a silicic acid raw material such as silica stone and a carbonaceous raw material is charged into a shaft furnace with auxiliary fuel added as necessary, and a high concentration of oxygen is supplied to the tuyere of the hearth of the shaft furnace. A combustion support gas containing the gas is blown in to form a high-temperature combustion zone, and molten tin or molten alloy mainly composed of tin and lead is poured from the upper part of the nine tuyeres, or they are solidified in the charge. The silicon produced in the shaft furnace high temperature section and the upper part of the furnace is dissolved in the molten metal, and the molten metal is taken out of the furnace and cooled, thereby precipitating and separating silicon or ferrosilicon from the bath water. A method for producing silicon or ferrosilicon, characterized by: