阅读说明：本技术 一种低品位含氟含硅废矿渣干法制备回收功能性超纯纳米二氧化硅生产工艺 (Production process for preparing and recovering functional ultra-pure nano silicon dioxide from low-grade fluorine-containing silicon-containing waste slag by dry method ) 是由 蔡景华 邵艳群 黄雨迪 雷游生 林德源 何佳润 于 2020-06-07 设计创作，主要内容包括：本发明具体涉及一种低品位含氟含硅废矿渣干法制备回收功能性超纯纳米二氧化硅生产工艺。本发明对含氟含硅矿渣采用中和剂、浮选剂、偶联剂的处理,经过两次的浮选工艺,可以充分对含氟硅渣尾矿资源加以综合利用,减轻了对天然硅矿的依赖,具有减少环境污染、获得超纯功能性纳米二氧化硅和缓解萤石资源压力的多重效益,并可回收到不同目数超纯SiO<Sub>2</Sub>,无须特殊设备,SiO<Sub>2</Sub>回收率可达99%以上。(The invention particularly relates to a production process for preparing and recovering functional ultrapure nano silicon dioxide from low-grade fluorine-containing silicon-containing waste slag by a dry method. The invention adopts the neutralizing agent, the flotation agent and the coupling agent to treat the fluorine-containing silicon-containing slag, can fully and comprehensively utilize the fluorine-containing silicon slag tailing resources through twice flotation processes, reduces the dependence on natural silicon ore, has multiple benefits of reducing environmental pollution, obtaining ultrapure functional nano silicon dioxide and relieving fluorite resource pressure, and can recover ultrapure SiO with different meshes 2 No need of special equipment, SiO 2 The recovery rate can reach more than 99%.)

1. A production process for preparing and recovering functional ultra-pure nano silicon dioxide from low-grade fluorine-containing silicon-containing waste slag by a dry method is characterized by comprising the following steps of: the method specifically comprises the following steps:

(1) adding the recycled wastewater and a neutralizer into the fluorine-containing silicon silicate slag, adjusting the pH, and heating and stirring the mixture for 2 hours at a constant temperature of 80 ℃ in a batching tank to obtain a batching A with the pH value of 8-9;

(2) taking the ingredient A, stirring at 70-80 ℃, adding a flotation agent until the pH is 7, filtering, washing precipitates with ultrapure water, dehydrating, and drying at 120 ℃ to obtain precipitates A;

(3) adding a KH570 coupling agent at room temperature, further performing flotation, filtration, cleaning and dehydration on the precipitate A, and then drying and cooling;

(4) and obtaining the ultra-pure silicon micro powder with different meshes after supersonic speed crushing and grading, cyclone dust removal or cloth bag dust removal.

2. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 1, which is characterized in that: the fluorine-containing silicic acid silicon slag comprises the following raw material components in percentage by mass: 35% by weight of water, F^-Content 6.5wt%, Si⁴⁺The content is 52wt%, and other impurities are 6.5 wt%.

3. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 2 is characterized in that: wherein F^-Is H₂SiF₆、SiF₄Or in the presence of HF; si⁴⁺Is SiO₂、H₂SiF₆Or SiF₄Are present.

4. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 1, which is characterized in that: the neutralizing agent in the step (1) is a self-made neutralizing agent, the purpose is to adjust the pH value of the waste residue to 7-8, and the neutralizing agent consists of alkali liquor, carbonate, a heavy metal catching agent and a stabilizing agent; wherein the heavy metal scavenger is ethionamide C₂H₅)₂NCSSNa·3H₂O, the addition amount of which accounts for 0.1-1.5 wt% of the neutralizer; wherein the stabilizer is a rare earth citric acid complex, and the addition amount of the stabilizer accounts for 0.1wt% of the neutralizer.

5. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 4, which is characterized in that: wherein the alkali solution is 50-70 wt% NaOH + 30-50 wt% NH₄OH; composition of the carbonate: 5g of Na₂CO₃+15g (NH₄)₂CO₃+15g NH₄HCO₃。

6. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 1, which is characterized in that: the flotation agent in the step (2) is composed of the following raw materials in percentage by mass: 30-60% of xanthate or xanthate derivative, 30-60% of oxalic acid, 1-3% of sodium dodecyl benzene sulfonate, 0.5-1% of other metal collecting agents, and the sum of the total mass fraction is 100%.

7. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 1, which is characterized in that: and (3) the mass ratio of the KH570 coupling agent to the precipitate A is 1: 8-1: 10.

8. The production process for preparing and recovering functional ultra-pure nano silicon dioxide by using the low-grade fluorine-containing silicon-containing waste slag through the dry method according to claim 1, which is characterized in that: the step (4) is to obtain 2000-mesh silicon dioxide after supersonic speed crushing and grading; then cyclone dust removal is carried out to obtain 5000-mesh functional silicon dioxide;

and collecting the dust generated after cloth bag dust removal through a pipeline dust remover and a trap to synthesize the nanoscale functional ultra-pure silicon micropowder.

Technical Field

The invention relates to a method for extracting silicon dioxide from slag, in particular to a production process for preparing and recovering functional ultra-pure nano silicon dioxide from low-grade fluorine-containing silicon-containing waste slag by a dry method.

Background

Natural silica has a density of 2.65 and a mohs hardness of 7, and is the second most abundant of all elements in the earth, but high quality natural silica is relatively small. Because the silicon ore belongs to non-pillar mineral resources of national economy in China and is also a plurality of non-metal mineral resources with undetermined reserves in China, the reserves in China are mostly predicted estimated numbers or unknown numbers. Displaying according to the related data: the silicon ore reserves in China reach 140 hundred million tons, and the vein quartz reserves with the silicon dioxide content of more than 99 percent are only 5000 million tons. Natural silicon ore is processed into micro powder through a plurality of processes such as mining, crushing, sand making, magnetic separation, flotation, roasting, acid washing, purification, high-purity water treatment and the like, and the micro powder is customarily called as 'sand' with the particle size of 20-200 meshes; those having a particle size of 200 mesh or more are called "fine silica powder".

Internationally, the leading technology of silicidation is united states, japan, germany, and the next is british, france. The Union of Enaming in the United states called "the highest purity quartz sand replacing crystals produced exclusively in the world", whose "IOTA quartz" was regarded as "international standard purity". Japanese chemical industry company and Nissian iron chemical industry company innovate and develop spherical silicon powder with high purity and low radioactive content, the purity reaches 99.99 percent, the spherical silicon powder is used for packaging large-scale and ultra-large-scale integrated circuits, and the ultra-pure silicon powder filler accounts for more than 70 percent of the components of the epoxy plastic packaging material in the chip technology. Japan is a world with a large output of epoxy plastic packaging materials, and accounts for about 90 percent of the world. In recent years, the world energy crisis and industry are upgraded and updated, so that the blowout development of the high-purity sand market is caused, the demand is greatly increased, and domestic production enterprises and scientific research institutions are increasing the strength to research silicon purification technology and obtain great progress, but have great difference with the world, and mainly show that three technical bottlenecks, namely purity, ultra-micro radiation and controllable crystal form, cannot be broken through.

At present, the silicon industry material enterprises in China have smaller group scale, and make little progress in respective production, particularly, the process is not wrong in the aspect of maintaining the product purity in the aspect of the production of quartz glass tube drawing materials, but the purification process is still at a lower level compared with the international level, so that the dependence on raw ores is extremely strong. Most purification processes are operated in a workshop way, so that the yield is limited. And the grade is to be improved. At present, 99.9% of enterprises can achieve the aim of no more than several enterprises with the grain size of less than 200 meshes; the purity of the silicon powder with the particle size of more than 200 meshes basically stays below 99.6 percent, the particle size is basically limited below 600 meshes, and the yield of the silicon powder with the particle size of more than 4000 meshes is very low; no enterprise can achieve the silicon micro powder with 8000 meshes to nano level; the purity of the tap of the world ultra-pure silicon micro powder industry, namely the product of the U.S. Uninidn company reaches the level of 99.9992 percent, and is close to 99.9994 percent, and the particle size and the shape are well controlled. The high-purity sand produced by high-purity silica sand enterprises in China is the target to replace American Union Nimin standard silica sand, but at present, the best level can only be similar, the crucible is taken as an outer layer and a middle layer of a crucible to replace materials, and the inner layer still uses high-purity sand produced by high-price imported American Union Nimin.

In order to reduce the dependence on natural silicon ore and the environmental pollution caused by mining and metallurgy waste ore, the raw materials of the invention are further waste, namely fluorine-containing silicon-containing waste slag, obtained after fluorite processing is primarily carried out on waste slag after metallurgy copper smelting, the water content is about 35 percent, the F-content is about 6.5 percent, and SiO is₂About 52% and about 6.5% are other impurities. Usually, waste residue is transported and then is buried, which not only pollutes the environment, but also needs a landfill site to occupy cultivated land. Over time, landfills are also a source of pollution. In addition, the silicon slag is packaged and transported by ton bags during transportation. The ton bag needs to be scrapped after being used for a plurality of times, so that new environmental pollution is caused. The fluorine-containing and silicon-containing waste slag is easy to scatter during the process of sending the waste slag into the next working procedure, and causes the environmental pollution along the way. The mode has high labor cost, the loading and unloading are finished by a forklift or a traveling crane, an operator needs to hold a special operation certificate, and the packaging cost is high. Of greater importanceThe fluorine-containing and silicon-containing waste slag has strong acidity, the pH value is less than 1 after several batches of detection, and special equipment is required for transportation and storage. HF in the fluorine-containing silicon-containing waste slag has strong corrosivity, can corrode all metals and even acid glass, and can rust attached substances even if a trace amount of HF remains. The waste produced by the invention can be further recycled.

Disclosure of Invention

The invention aims to provide a production process for preparing and recovering functional ultra-pure nano silicon dioxide from low-grade fluorine-containing and silicon-containing waste slag by a dry method. The method can fully and comprehensively utilize the fluorine-containing silicon slag tailing resources, reduces the dependence on natural silicon ore, and has multiple benefits of reducing environmental pollution, obtaining ultra-pure functional nano silicon dioxide and relieving the pressure of fluorite resources.

In order to achieve the purpose, the invention adopts the following technical scheme:

a production process for preparing and recovering functional ultra-pure nano silicon dioxide from low-grade fluorine-containing silicon-containing waste slag by a dry method (the flow is shown in figure 1); the method specifically comprises the following steps:

(1) adding the recycled wastewater and a neutralizer into the fluorine-containing silicon silicate slag, adjusting the pH, and heating and stirring the mixture for 2 hours at a constant temperature of 80 ℃ in a batching tank to obtain a batching A with the pH value of 8-9;

(2) taking the ingredient A, stirring at 70-80 ℃, adding a flotation agent until the pH is 7, filtering, washing precipitates with ultrapure water, dehydrating, and drying at 120 ℃ to obtain precipitates A;

(3) adding a KH570 coupling agent at room temperature, further performing flotation, filtration, cleaning and dehydration on the precipitate A, and then drying and cooling;

(4) and obtaining the ultra-pure silicon micro powder with different meshes after supersonic speed crushing and grading, cyclone dust removal or cloth bag dust removal.

Further, the fluorine-containing silicic acid silicon slag comprises the following raw material components in percentage by mass: 35% by weight of water, F^-Content 6.5wt%, Si⁴⁺The content is 52wt%, and other impurities are 6.5 wt%.

Wherein F^-Is H₂SiF₆、SiF₄Or in the presence of HF; si⁴⁺Is SiO₂、H₂SiF₆Or SiF₄Are present.

Further, the neutralizing agent in the step (1) is a self-made neutralizing agent, the purpose of the self-made neutralizing agent is to adjust the pH value of the waste residue to 7-8, and the neutralizing agent consists of alkali liquor, carbonate, a heavy metal catching agent and a stabilizing agent; wherein the heavy metal scavenger is ethionamide (C)₂H₅)₂NCSSNa·3H₂O), the addition amount of which accounts for 0.1-1.5 wt% of the neutralizer; wherein the stabilizer is organic rare earth, and the addition amount of the stabilizer accounts for 0.1wt% of the neutralizer.

Further, the alkali solution is 50-70 wt% NaOH + 30-50 wt% NH₄OH; composition of the carbonate: 5g of Na₂CO₃+15g (NH₄)₂CO₃+15g NH₄HCO₃。

Further, the flotation agent in the step (2) is composed of the following raw materials in percentage by mass: 30-60% of xanthate or xanthate derivative, 30-60% of oxalic acid, 1-3% of sodium dodecyl benzene sulfonate, 0.5-1% of other metal collecting agents, and the sum of the total mass fraction is 100%.

Further, the mass ratio of the KH570 coupling agent to the precipitate A in the step (3) is 1: 8-1: 10.

Further, the step (4) is specifically to obtain 2000-mesh silicon dioxide after supersonic speed crushing and classification; then cyclone dust removal is carried out to obtain 5000-mesh functional silicon dioxide; and collecting the dust generated after cloth bag dust removal through a pipeline dust remover and a trap to synthesize the nanoscale functional ultra-pure silicon micropowder.

The flotation agent has the advantages of high flotation speed, less and fine foam, simple formula and low price. The sediment after flotation can be used for purifying silica sand, and the liquid can further use synthetic fluorite.

The basic principle is as follows:

H₂SiF₆→SiF₄+HF

SiF₄+ H₂O ↔ SiO₂+ 4HF

HF+OH^-→Na⁺+F^-+H₂O

HF+NH₄OH→NH₄ ⁺+F^-+H₂O

SiF₄+Na₂CO₃ ^2-→Na⁺+F^-+Si₂(CO₃)₄↓

Si₂(CO₃)₄+CH₃CCH₂-OO(CH₂)₃Si(OCH₃)₃→SiO₂↓+CO₂+H₂O

wherein the selection and operation of the flotation reagent are the most important steps in the flow. The flotation agent which is independently researched and developed by the invention is prepared according to different slag sources, so that the flotation effect is good, the consumption is low, and the pollution is small. And washing with tap water or ultrapure water after flotation.

Further, the drying in the step (3): drying the centrifuged material by high-temperature heating and microwave heating to remove CO₂And collecting CO₂。

The invention has the following remarkable advantages:

(1) the invention fully and comprehensively utilizes the fluorine-containing silicon slag tailing resources, lightens the dependence on natural silicon ore, and has multiple benefits of reducing environmental pollution, obtaining ultra-pure functional nano silicon dioxide and relieving the pressure of fluorite resources.

(2) In the process of the invention, the wastewater, the dust and the solid waste are all recycled.

(3) The process can recover ultrapure SiO with different meshes₂No need of special equipment, SiO₂The recovery rate can reach more than 99%.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 SEM image of the product of example 3.

Detailed Description

For further disclosure, but not limitation, the present invention is described in further detail below with reference to examples.