JPS616112A - Manufacture of metallic silicon - Google Patents

Abstract

PURPOSE:To obtain high purity metallic Si free from Fe and Al by blowing gaseous hydrocarbon into a fluidized bed of SiO2 powder at a high temp. and heating a formed SiO2-SiC mixture to a higher temp. to form metallic Si by a reaction and melting. CONSTITUTION:A gas such as Ar or H2 is introduced into the fluidized bed body 1 provided with a built-in heater 4 from a lower gas blowing hole 9, and SiO2 powder and gaseous hydrocarbon are blown from blowing pipes 8, 3 to form a fluidized bed. At the same time, they are brought into a reaction at >=1,300 deg.C. A formed SiO2-SiC mixture is collected and recovered from a product outlet 7. The mixture is put in a plasma melting furnace or the like provided with a water-cooled crucible 11, and it is heated to a higher temp. to form metallic Si 14 by a reaction and melting. At this time, a regulating agent such as SiC, solid carbon powder or SiO2 powder are added to the mixture as required. By this method, high purity metallic Si can be manufactured easily.

Description

DETAILED DESCRIPTION OF THE INVENTION <Object 1> Industrial Application Field The present invention relates to a method for producing a metal I'' element (hereinafter referred to as metal Si), and in detail, [e, ■! The present invention relates to a method for producing high-purity metal S1 that does not contain impurities such as , ^1, etc.

Conventional Technology In the past, metal S1 was generally produced by reducing the reduction of silica (silica stone) with solid carbon in an electric furnace. In such a method, since coal or coke is usually used as the carbonaceous material, impurities contained in these carbonaceous materials, such as [e,
etc. are reduced at the same time and enter the metal Si, so the purity of the metal S1 obtained is as low as 90-95%. Since purification by a purification process is necessary, and the efficiency of this purification process also depends on the purity of the original gold fiS1, it has been desired to develop a method for producing high-purity metal Si that does not contain Fe, ■1, Al, etc. .

Problems to be Solved by the Invention The present invention aims to solve these problems. Specifically, in place of solid carbon, which is the cause of lowering purity, SiO and [
e. (1) Propose a method for producing high-purity gold BS1 that does not contain Al.

<Structure of the Invention> The present invention is a means to solve the problem.The present invention is a method of injecting hydrocarbon gas into the fluidized fluid (3) in which 8102 powder is fluidized at a temperature of 1300°C or more, The process consists of a first step in which the above is converted into SiC, and a second step in which the mixture of SiO2 and SiC produced in the first step is further heated to a high temperature and reacted and dissolved.
shall be.

The present invention will be explained in detail below.

FIG. 1 is a longitudinal sectional view of an example of an apparatus showing an embodiment of the first step of the present invention, and FIG. 2 is a longitudinal sectional view of an example of the apparatus showing an embodiment of the second step.

In Fig. 1, a non-oxidizing, non-nitriding gas such as Ar, H, etc. is introduced as a fluidized bed forming gas through the lower gas inlet 9 of the fluidized bed body 1 which has a resistor heater 4 inside. , SiO2 gas and hydrocarbon gas are continuously blown into the respective blowing pipes 8 and 3 to form a fluidized bed 130.
The reaction is carried out at a temperature of 0°C or higher. The reaction product is collected by cyclone 5 and recovered from the product lower.

Fluidized bed temperature gN 300°C or higher, preferably 1300~
A temperature of 1,450°C is required; below 1,300°C, the reaction does not proceed, and above 1,450°C, the decomposition of hydrocarbons becomes severe and the amount of waste as S10 increases. For heat supply, in addition to direct heating using a resistor as shown in Figure 1, indirect heating from outside the fluidized bed may be used, but using combustion exhaust gas is not recommended due to the concentration of gas in the furnace. This is inappropriate because it is necessary to keep the value low. In addition, if the hydrocarbons injected into the fluidized bed are preheated to a high temperature, the hydrocarbons will decompose and precipitate carbon before reacting with 8102, resulting in Si
Since the reduction reaction of O2 will not proceed, decomposition can be suppressed by blowing directly into the high temperature fluidized bed without preheating.
If the reduction reaction in step 2 can proceed effectively.

In addition, in the reduction reaction of SiO2, in order to obtain the optimum composition ratio in the second step, more than 40% of the charged SiO2 is Si.
It is necessary to be reduced to C, and below this it is gold @ S
The productivity of i decreases and the high purity SiO2 raw material is wasted, resulting in poor efficiency.

The next second step is not limited to hCl, which can be carried out more advantageously by using a conventional transfer-type plasma melting furnace having a water-cooled crucible 11 as shown in FIG. 2nd step - (.) The product of the 1st step is put into a second furnace kept at a high temperature, and metal Si is
obtained in molten state. In order to proceed with the reaction (1) efficiently, the S i /CfJi 17i ratio should be 3.3 to 4.2.
, especially preferably within 3.5. Even if the diameter is larger or smaller than this, the yield of gold 1iisi will decrease. Therefore, the product from the first process is usually used as is in the second process, but using the above-mentioned f/3.5 range as a guideline, it is not acceptable, and if it is out of the range, a conditioning material is added and mixed. . That is, if it is significantly larger than 3.5, high purity SiC is added and mixed, and if it is significantly smaller than 3.5, 3i02y) powder is added and -(S1/・C
The weight ratio is 3.5, and it can be used as is or straight.
llllll beret (~'); 8 charged into the cracking furnace.

Further, in the above-mentioned component adjustment, the same effect can be obtained by adding high-purity solid carbon (for example, carbon black) in place of -61S or all of SiC. In this case, the second step is SiO2 + 2C-+Si+
Since the reaction 2GO proceeds simultaneously, the same effect as that of SiC addition can be obtained by changing the weight ratio of Si/C in the mixture after adding solid carbon to the following formula, based on the chemical m hr St calculation. can get.

12×Y Here, Y [SiO2 /SiC of the finished product in the first step
is the weight ratio of

In the melting furnace of the second step, the temperature is 1900℃ or higher when no diluent gas is introduced at normal pressure, preferably 1900 to 200℃.
A temperature of 0°C is required; below this temperature, the generation of cored Si cannot be achieved, and above 2000''C, the evaporation loss of SiO or Si increases, resulting in a deterioration of the yield.7:H2
It is possible to lower the reaction temperature by using a boundary gas such as , Ar, or by conducting the reaction under reduced pressure to lower the 00 partial pressure of the reaction system. , the reaction can be avoided at temperatures of 1800°C or higher.

As mentioned above, the present invention can be applied to all currently manufactured SiO2 powders if they are commercially available, but the present invention is effective when the raw material is as pure as possible, for example, 98% or more. In particular, it can be applied to SiO,+ powder with a high purity of 99% or even 99.999% or higher.

In the above, the mixture produced in the first step is Si
It consists of C and unreacted SiO2. However, in the first step, in addition to these compositions, a small amount of metal S1 is produced and some C remains, so the mixture mainly consists of SiC and unreacted SiO2. There are, but
In addition, metals such as Si and C are included.

In addition, the SiC produced in the first culm (J) is roughly classified into β-SiC and α-3iC based on its crystal structure, but in the method of the present invention, the SiC produced is either of these 8I structures. Even if there is, there is no problem.

Example Using the reaction apparatus shown in Figures 1 and 2, ikq/11
Gold l11si was produced at the same capacity.

In other words, in the first step, the AVJ gas is heated to iNm' TH2 from the lower part of a fluidized fluidized furnace with a built-in resistor heater inside.
/h, SiO2 powder and cold methane gas were continuously blown in at a rate of 1.3 kQ/h and 4.5 NmJ/h+7), respectively, and the reaction product was recovered with an icron.

The methane gas and ■2 gas used were both 99.999.
The raw material Sin, 114 degrees is 'J9.999%, and the operating conditions are as shown in Table 1+a.
As shown in Figure 1, the reaction was carried out at 1380°C, the Si/0 weight ratio of the product was 41, and the power consumption was 20:1 vH.

The second step is a normal transfer 5' which has a water-cooled crucible with Ar working waste as shown in FIG. A gamma lasma melting furnace was used.

1] Add high-purity J-Pump rack to the reaction product obtained in step 2, charge it into a melting furnace as a mini pellet with a diameter of 3 nm + m, and conduct the melting reaction at a temperature of 2000'C. The metal S1 was recovered. Operation Article 1'l (Table 1)
As shown in b), the input amount of Belen i is 2.2 kq/h,
Ar Nagareyama is 2Nm'/h, °gravity consumption! 'tl Lj
There is 9 kwll-C++ ('1 The amount of produced metal Si is 850 su, / h ”(: !11! degree 1; t, 9
At 9.999% or more, "e, 1;, to lS! 7 impurities (
J gold (including) was written.

Table 1 (al 1st ■ culm fbl th knee r culm (
Effects of the invention: As explained in detail above, three easily purified hydrocarbons are
Reduce SiO2 as a primary agent, and convert metal S1 in about 2]!
l! I was able to easily obtain a high-purity metal S1 containing no Al at all.

The high purity metal S1 obtained in the present invention can be used not only for solar cells but also as a raw material for semiconductors.

[Brief explanation of the drawing]

FIG. 1M is a vertical sectional view of an apparatus showing an example of the actual @H method of the first step of the present invention, and FIG. 2 is a longitudinal sectional view of the apparatus showing an example of an embodiment of the second step. Code 1: Fluid decoy body 2: Gas distribution plate 3: GH4 blowing pipe 4: Heating heater 5: Zyclone 6. ...131 Gas outlet lower ... Product outlet 8 ... Preheated SiO2 powder injection pipe 9 ...
・Heating scum inlet

Claims (1)

[Claims] 1) Hydrocarbon gas is blown into a fluidized bed in which SiO_2 powder is fluidized at a temperature of 1300°C or higher, and 40% of SiO_2
A method for manufacturing silicon metal, characterized by comprising a first step of converting the above into SiC, and a second step of heating the mixture containing SiO_2 and SiC produced in the first step to a higher temperature and reacting and dissolving it. . 2) Hydrocarbon gas is blown into a fluidized bed in which SiO_2 powder is fluidized at a temperature of 1300°C or higher, and 40% of SiO_2
The SiO_2 produced in the first step consists of a first step in which the above is converted into SiC, and a second step in which the mixture containing SiO_2 and SiC produced in the first step is further heated to a high temperature and reacted and dissolved. and SiC in a mixture containing S
A method for producing metallic silicon, characterized in that after adding at least one regulator of iC and/or solid carbon powder or SiO_2 powder, the mixture is reacted and dissolved in the second step.