CN103663459B

CN103663459B - A kind of method combining liquation refining purifying industrial silicon

Info

Publication number: CN103663459B
Application number: CN201310642445.5A
Authority: CN
Inventors: 王志; 胡磊
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2013-12-03
Filing date: 2013-12-03
Publication date: 2016-08-17
Anticipated expiration: 2033-12-03
Also published as: CN103663459A

Abstract

A kind of method combining liquation refining purifying industrial silicon, belongs to one and prepares solar-grade high-purity silicon technology.Industrial silicon and kamash alloy are heated to complete congruent melting by the method, and cooling makes silicon recrystallization separate out, and are heated to complete congruent melting after silicon metal pickling with acieral, and cooling makes silicon separate out, carries out directional solidification after silicon metal pickling, and ingot casting, stripping and slicing obtain high purity polycrystalline silicon.The method operation temperature, below 1400 DEG C, can make boron, the content of phosphorus impurities is reduced to the requirement of solar energy level silicon.

Description

A kind of method combining liquation refining purifying industrial silicon

Technical field

The present invention relates to one and prepare solar-grade polysilicon technology, particularly to a kind of method combining liquation refining purifying industrial silicon.

Background technology

Fast development along with photovoltaic industry, the demand of solar-grade polysilicon is increased dramatically, there is the problems such as energy consumption is high, cost is high and seriously polluted owing to the chemical methods such as Siemens Method produce solar energy polycrystal silicon technology, metallurgy method prepares polycrystalline silicon technology becomes focus of attention.

Metallurgy method is on the premise of not changing body silicon character, by the impurity in pickling, directional solidification, gasification-slag refining, vacuum metling, high energy beam (electronics, ion) a series of combined methods such as method, alloy liquation refining removing metalluragical silicon, being a kind of purification technique step by step to impurity operation, whole enabling objective product silicon is all in condensed state.

Owing to the fusing point of silicon is high (1410 DEG C), metallurgy method purification process need to make it be in high temperature condensed state all the time.Under condensed state, the metal impurities in silicon are huge with available unbundled attribute differences such as the segregation coefficient of nonmetallic inclusion, oxidation-reduction quality and saturated vapor pressures.Separate it is thus impossible to use a kind of separation means to complete all impurity with silicon, so the multiple separation method of the many employings of metallurgy method carries out sequential combination remove impurity.But owing to impurity separation coefficient is little, purification process transmission is little with reaction motive force, and the separation efficiency causing unit process impurity is low.Metallurgy method at present the most only by unilateral raising refining treatment temperature, extend the purification time, the modes such as purification step and number of times that increase meet index needed for silicon purity so that the big multi tate of metallurgy method technique is slow, efficiency is low, power consumption is high, product is unstable.These shortcomings cause metallurgy method to be difficult to become the proprietary production technology of solar-grade polysilicon.

The patent of Zhao Lixin, Wang Zhi et al. application: method (Patent No. 2010100620791.X of a kind of removing boron and phosphorus in silicon at a low temperature, date of declaration is on June 29th, 2011), this invention relates to a kind of method of removing boron and phosphorus in silicon at a low temperature, industrial silicon is passed through broken pickling pretreatment by the method, complete congruent melting is heated with kamash alloy, cooling makes silicon recrystallize precipitation, the quick ingot casting of silicon metal, the HIGH-PURITY SILICON that broken pickling can obtain boron, phosphorus content is low.But the content of boron phosphorus and typical metal impurity is the highest in the HIGH-PURITY SILICON that the method obtains, do not reach the requirement of solar-grade polysilicon, owing to stannum solid solubility in silicon is bigger, maximum solid solution degree is up to 5335ppmw, in the HIGH-PURITY SILICON obtained in this way, the content of stannum is the highest, is unfavorable for the ingot casting removal to stannum.

Summary of the invention

It is an object of the invention to provide a kind of method combining liquation refining purifying industrial silicon, overcome the shortcomings such as the most efficiency of metallurgy method technique is low, power consumption is high, product is unstable, effectively remove boron, phosphorus and metal impurities.

The production method of industrial silicon is refined in the combination liquation refining of the present invention: kamash alloy is heated to complete congruent melting, cooling makes silicon recrystallize, silicon metal is heated to complete congruent melting after pickling with acieral, cooling makes silicon crystallize, solidification growth it is oriented again after silicon metal pickling, ingot casting stripping and slicing, obtains HIGH-PURITY SILICON.The method includes following each step:

(1) industrial silicon is broken for granularity and is less than 500 micron particle, and screening obtains 150～500 microns of silica flours, cleans 4～8 times with deionized water, dries；

(2) by the industrial silica fume obtained in step (1) and kamash alloy Hybrid Heating, until being completely melt as liquid, liquid phase fused mass is cooled down, make silicon liquate crystallization, through Solid-Liquid Separation, and it is broken for granularity less than 500 micron particle, then pickling, rinse and dry, obtain recrystallized silicon.Wherein silica flour is 1:1～1:100 with the weight ratio of kamash alloy, and heating fusion temperature is 300～1500 DEG C, and the cooldown rate of liquate process is 0.1～10 DEG C/min；

(3) recrystallized silicon step (2) obtained and acieral Hybrid Heating, until being completely melt into liquid, to be cooled down by liquid phase fused mass, make silicon liquate crystallization, through Solid-Liquid Separation, and be broken for granularity less than 500 micron particle, then pickling, rinse and dry, obtain recrystallized silicon.Wherein silica flour is 1:0.1～1:100 with the weight ratio of acieral, and heating fusion temperature is 600～1500 DEG C, and the cooldown rate of liquate process is 0.1～10 DEG C/min.

(4) recrystallized silicon that step (3) obtains is oriented solidification growth, ingot casting stripping and slicing, obtains solar-grade high-purity silicon.

Kamash alloy described in step (2) is stannum, aluminum, copper, nickel, ferrum and gallium, or two or more mixture between them, and purity is 99%～99.999%.

Acid described in step (2) and step (3) is hydrochloric acid, sulphuric acid, nitric acid, chloroazotic acid, Fluohydric acid., acetic acid, or two kinds and two or more mixture between them.

Solid-Liquid Separation mode described in step (2) and step (3) is centrifugation, filter pressing or sucking filtration.

The kamash alloy of the solid-liquid separation described in step (2) is circularly used for melting the silica flour that step (1) obtains.

Acieral described in step (3) is aluminum, stannum, copper, nickel, ferrum and gallium, or two or more mixture between them, and purity is 99%～99.999%.

The acieral of the solid-liquid separation described in step (3) is circularly used for melting the silica flour that step (2) obtains.

Ingot casting speed described in step (4) is 1～200mm/h.

Present invention advantage compared with prior art is:

(1) the inventive method is recrystallization purification method based on chemical field, and metalluragical silicon can be made to melt at low temperatures, it is achieved the trace impurity quick removal below silicon fusing point in silicon.

(2) present invention is compared with conventional metallurgical method, it is possible to effectively reduce energy consumption.Compared with a liquation refining, substantially increasing purification efficiency, and effectively reduce liquate medium carrying secretly in silicon, beneficially directional solidification is for the removal of liquate medium.

Detailed description of the invention

Embodiment 1:

Becoming particle diameter to be less than 500 micron particle through crushing grinding 10kg industry silico briquette (trade mark 1101, Hunan, the place of production), screening obtains the silica flour of 150～500 microns.Take 100g silica flour to carry out washing, drying, obtain pretreatment silica flour.The silica flour of pretreatment is mixed with metallic tin (purity is 99.99%), is heated to 1300 DEG C and is completely melt, be cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.The silica flour obtained mixes with metallic aluminium (purity is 99.99wt%), is heated to 1300 DEG C and is completely melt, is cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.The silica flour obtained is oriented solidification growth, and ingot casting stripping and slicing obtains HIGH-PURITY SILICON.Purification the results are shown in Table 1.

Table 1

Impurity element	Al	B	Ca	Cu	Fe	Mn	Ni	P	Sn	Ti	V
												Industrial silicon	1767	12	134	33	2135	259	214	242	13	298	283
HIGH-PURITY SILICON	2.5	0.28	0.0	0.0	0.0	0.0	0.0	0.46	1.1	0.0	0.0

Unit: ppmw

Embodiment 2:

Becoming particle diameter to be less than 500 micron particle through crushing grinding 10kg industry silico briquette (trade mark 1101, Hunan, the place of production), screening obtains the silica flour of 150～500 microns.Take 100g silica flour to carry out washing, drying, obtain pretreatment silica flour.The silica flour of pretreatment is mixed with the useless stannum of centrifugation in embodiment 1, is heated to 1300 DEG C and is completely melt, be cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.The silica flour obtained mixes in embodiment 1, is heated to 1300 DEG C and is completely melt, is cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:10, is rinsed by silica flour, dries after pickling.The silica flour obtained is oriented solidification growth, and ingot casting stripping and slicing obtains HIGH-PURITY SILICON.Purification the results are shown in Table 2.

Table 2

Impurity element	Al	B	Ca	Cu	Fe	Mn	Ni	P	Sn	Ti	V
												Industrial silicon	1767	12	134	33	2135	259	214	242	13	298	283
HIGH-PURITY SILICON	3.2	0.33	0.0	0.0	0.0	0.0	0.0	0.58	1.7	0.0	0.0

Unit: ppmw

Embodiment 3:

Becoming particle diameter to be less than 500 micron particle through crushing grinding 10kg industry silico briquette (trade mark 1101, Yunnan, the place of production), screening obtains the silica flour of 150～500 microns.Take 100g silica flour to carry out washing, drying, obtain pretreatment silica flour.The silica flour of pretreatment is mixed with metallic tin (purity is 99.9%), is heated to 1250 DEG C and is completely melt, be cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:20, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:20, is rinsed by silica flour, dries after pickling.The silica flour obtained mixes with metallic aluminium (purity is 99.9wt%), is heated to 1300 DEG C and is completely melt, is cooled to room temperature with 3 DEG C/min.Centrifugation silicon crystal, is that granularity is less than 500 micron particle by silicon crystal, and with 5wt% Fluohydric acid. at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:20, is rinsed by silica flour, dries after pickling.Then with 20wt% chloroazotic acid at 70 DEG C of pickling 6h, reaction solid-to-liquid ratio is 1:20, is rinsed by silica flour, dries after pickling.The silica flour obtained is oriented solidification growth, and ingot casting stripping and slicing obtains HIGH-PURITY SILICON.Purification the results are shown in Table 3.

Table 3

Impurity element	Al	B	Ca	Cu	Fe	Mn	Ni	P	Sn	Ti	V
												Industrial silicon	1123	9.0	86	45	1654	212	236	137	18	187	243
HIGH-PURITY SILICON	3.7	0.41	0.0	0.0	0.0	0.0	0.0	0.58	1.9	0.0	0.0

Unit: ppmw.

Claims

1. the method combining liquation refining purifying industrial silicon, it is characterised in that: comprise the following steps:

(1) industrial silicon is broken for granularity and is less than 500 micron particle, and screening obtains 150～500 microns of silica flours, Clean 4～8 times with deionized water, dry；

(2) industrial silica fume that step (1) is obtained and kamash alloy Hybrid Heating, until be completely melt into Liquid, cools down liquid phase fused mass, makes silicon crystallization, through Solid-Liquid Separation, broken, pickling, drift Washing and dry, obtain recrystallized silicon, wherein silica flour is 1:1～1:100 with the weight ratio of kamash alloy, adds Heat fusing temperature is 300～1400 DEG C, and the cooldown rate of liquate process is 0.1～10 DEG C/min；

(3) recrystallized silicon that step (2) is obtained and acieral Hybrid Heating, until be completely melt into Liquid, cools down liquid phase fused mass, makes silicon crystallization, through Solid-Liquid Separation, broken, pickling, drift Washing and dry, obtain recrystallized silicon, wherein silica flour is 1:0.1～1:100 with the weight ratio of acieral, adds Heat fusing temperature is 600～1400 DEG C, and the cooldown rate of liquate process is 0.1～10 DEG C/min；

(4) recrystallized silicon that step (3) obtains is oriented solidification growth, ingot casting stripping and slicing, obtains too Sun can level polysilicon.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: Acid described in step (2) and step (3) is hydrochloric acid, sulphuric acid, nitric acid, chloroazotic acid, Fluohydric acid., acetic acid, Or two kinds and two or more mixture between them.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: Solid-Liquid Separation mode described in step (2) and step (3) is centrifugation, filter pressing or sucking filtration.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: The kamash alloy of the solid-liquid separation described in step (2) can be cycled to used in the silica flour that fusing step (1) obtains.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: The acieral of the solid-liquid separation described in step (3) is circularly used for melting the silica flour that step (2) obtains.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: Acid described in step (3) can be recycled in step (2) and use.

The method of combination liquation refining purifying industrial silicon the most according to claim 1, it is characterised in that: Ingot casting speed described in step (4) is 1～200mm/h.