Arsenic removal method for arsenic-containing crude antimony

Abstract

The invention relates to the field of antimony smelting, and particularly discloses an arsenic removal method of arsenic-containing crude antimony, which comprises the following steps: stirring and refining the arsenic-containing crude antimony and an iron-loaded composite material in a protective atmosphere at 750-1000 DEG C, carrying out alloying reaction on As in the arsenic-containing crude antimony and iron in the iron-loaded composite material to form FeAs alloy-loaded scum, and then carrying out slagging-off treatment to obtain the arsenic-containing crude antimony. The arsenic and antimony removed melt is obtained; the iron-loaded composite material comprises a carrier and an iron elementary substance immobilized on the carrier, the density is lower than 3 g / cm < 3 >, and the mass of iron added into the iron-loaded composite material is 1-2 times of the theoretical quantity required for transforming As into FeAs. The novel arsenic removal method provided by the invention is good in arsenic removal effect, simple to operate and low in raw material price, and has a very good application value.

Description

Technical Field

[0001] The invention relates to the technical field of crude antimony refining, and in particular to the field of arsenic removal from arsenic-containing crude antimony. Background Art

[0002] Antimony is a very important nonferrous metal, widely used in fireproof material manufacturing, photovoltaic glass manufacturing, lead storage, biopharmaceuticals and other industries. Due to the similar physical and chemical properties of arsenic and antimony, the raw material stibnite used in antimony smelting is often accompanied by a large amount of arsenic. The crude antimony obtained by pyrometallurgy and hydrometallurgy often contains 0.3-3% arsenic. Arsenic is extremely toxic, so the antimony smelting industry has extremely high requirements for the arsenic content in antimony. The crude antimony obtained by smelting needs to be further refined to meet the requirements of GB / T 1599-2014.

[0003] At present, the refining of crude antimony mainly adopts the process of oxidation refining, which takes advantage of the difference between the affinity of arsenic and antimony for oxygen. Soda ash or caustic soda flakes are added to the crude antimony as a slag-making agent, and air is used as an oxidant to oxidize the arsenic in the crude body into sodium arsenate, which enters the refining slag to remove the arsenic in the crude antimony. However, this process converts arsenic into Na 3 AsO 4 , due to Na 3 AsO 4 It is easily soluble in water. If it is not handled properly, it is very easy to cause soil and groundwater pollution in the area where the smelter is located. At the same time, when adding soda ash or caustic soda flakes to crude antimony as a slag-making agent for oxidation refining and arsenic removal, a large amount of antimony is also oxidized and reacts with soda ash or caustic soda flakes to form sodium antimonate. These Na 3 SbO 4 with Na 3 AsO 4 Excessive amounts of soda ash flakes form highly toxic arsenic alkali slag. At the current smelting level, about 150 to 200 kg of arsenic alkali slag is produced for every ton of antimony produced. Currently, about 20,000 tons of oxidized refined arsenic alkali slag is produced worldwide each year. However, the antimony smelting industry currently lacks a clean, efficient and harmless treatment technology for arsenic alkali slag, which leads to large-scale storage of arsenic alkali slag, posing a huge risk of environmental pollution. At the same time, the sodium antimonate contained in it is difficult to recycle, which not only causes a waste of resources, but also generates huge storage costs for antimony smelting companies.

[0004] Therefore, the industry is in urgent need of a method that is free of environmental burdens such as arsenic alkali slag hazardous waste and has excellent arsenic removal effect and selectivity. Summary of the invention

[0005] In view of the problems that the existing arsenic removal process for crude antimony containing arsenic has unsatisfactory arsenic removal effect and is prone to bring serious environmental pressure, the purpose of the present invention is to provide a method for removing arsenic from crude antimony containing arsenic, aiming to provide a harmless arsenic removal process with excellent arsenic removal effect and selectivity, and without environmental pressure such as arsenic alkali slag hazardous waste.

[0006] A method for removing arsenic from arsenic-containing crude antimony, comprising stirring and refining the arsenic-containing crude antimony and an iron-containing composite material in a protective atmosphere at a temperature of 750-1000° C., so that As in the arsenic-containing crude antimony and iron in the iron-containing composite material undergo an alloying reaction and form a slag containing FeAs alloy (referring to a general term for iron-arsenic alloys), and then performing a slag removal treatment to obtain an arsenic-removed antimony melt;

[0007] The iron-loaded composite material comprises a carrier and an iron element fixed thereon; the density of the carrier is less than 3 g / cm 3 ,

[0008] The mass of iron in the added iron-loaded composite material is 1 to 2 times the theoretical amount required to transform As into FeAs.

[0009] In order to solve the problem of selective arsenic removal from arsenic-containing crude antimony, the present invention is the first in the industry to attempt to propose a technical idea for achieving arsenic removal from crude antimony based on Fe-As alloying. However, it was discovered in the early stages of research and development that in order to successfully implement this new arsenic removal idea for the first time, many unique technical difficulties need to be overcome. For example, Fe can form an alloy with As, but it can also alloy with Sb. The use of iron for alloying arsenic removal requires solving the problem of selectivity of alloying with As and Sb. In addition, due to its properties, the Fe-As alloying product cannot be highly selectively separated from Sb, and alloying arsenic removal cannot be truly achieved. In order to solve the problem of removing arsenic from crude antimony using the Fe-As alloying idea, the present invention has conducted in-depth research and innovatively pre-fixed iron, and further coordinated the joint control of parameters such as temperature, specific gravity, and dosage during the refining process. This can achieve synergy and effectively improve the arsenic removal effect and selectivity in crude antimony. In addition, it can also avoid arsenic alkali slag and H 3 As high-risk gas release and other environmental pressures can meet process application requirements.

[0010] In the present invention, there is no special requirement for the arsenic content in the arsenic-containing crude antimony. However, considering the excellent arsenic removal effect and environmental advantages of the process of the present invention, it can be applied to relatively high-content arsenic-containing crude antimony for industrial value considerations. For example, the arsenic content in the arsenic-containing crude antimony can be 0.01 to 10.0 wt.%, and can further be 1.5 to 5 wt.%.

[0011] In the present invention, the iron-loaded composite material can be realized based on known immobilization means, for example, the iron-loaded composite material is immobilized on a carrier by chemical reduction or electrochemical reduction of an iron source;

[0012] Preferably, the iron source is a ferrous iron and / or ferric iron compound;

[0013] Preferably, the carrier is at least one of porous carbon, zeolite and diatomaceous earth.

[0014] In the present invention, the iron content of the iron-loaded composite material is 5 to 35 wt.%, preferably 10 to 30 wt.%;

[0015] Preferably, the particle size of the iron-loaded composite material is 1 to 5 mm;

[0016] Preferably, the density of the iron-loaded composite material is 1 to 2.5 g / cm 3 .

[0017] In the present invention, a melt containing arsenic and crude antimony can be obtained in advance, and then the iron-carrying composite material is added and refined at the temperature and protective atmosphere.

[0018] Preferably, the mass of iron in the added iron-loaded composite material is 1 to 1.5 times the theoretical amount required to transform As into FeAs.

[0019] In the present invention, the heating equipment in the refining stage is used to avoid introducing reactive gases into the reaction system as much as possible. For example, in the present invention, a particularly suitable heating equipment is an electric furnace.

[0020] In the present invention, the temperature in the refining stage is 750-900° C. The present invention has shown that refining at this temperature is helpful to further improve the selectivity of the reaction and the removal effect and selectivity of As.

[0021] In the present invention, the protective gas is a gas that does not contain any gas that can participate in the reaction, and is preferably at least one of nitrogen and an inert gas.

[0022] In the present invention, the stirring method in the refining stage is gas stirring and / or mechanical stirring;

[0023] Preferably, the gas used for the gas agitation is a protective gas;

[0024] Preferably, if the gas stirring method is adopted, the time of introducing the gas into the reaction is 1 to 4 hours, and the gas flow rate is 2 to 5 m / t of antimony. 3 / min input;

[0025] If mechanical stirring is used, the reaction time is 1.5 to 4 hours, and the melt rotation rate is 10 to 50 rpm.

[0026] In the present invention, after the stirring refining is completed, the melt is allowed to stand for 0.5 to 1 hour before slagging.

[0027] Beneficial Effects

[0028] The process of the present invention innovatively refines the iron-bearing composite material and the arsenic-containing crude antimony, and further adjusts the parameters in the preparation process, so that FeAs alloy (for example, FeAs, Fe2 As、Fe 3 As 2 alloy form), and can selectively reduce FeSb 2 , Fe 3 Sb 2 , Fe-As-Sb reaction, and in addition, it is also conducive to the selective separation of slag and antimony liquid. In this way, the efficient and highly selective removal of As in arsenic-containing crude antimony can be successfully achieved based on the Fe-As alloying idea, and the output of waste, solid waste and waste gas can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Process flow chart of the present invention DETAILED DESCRIPTION

[0030] The following examples are intended to further illustrate the present invention, but are not intended to limit the present invention.

[0031] In the following cases, the As content in the prime arsenic-containing crude antimony refers to the weight percentage.

[0032] The present invention is the first in the industry to propose an idea of ​​selectively removing arsenic from crude antimony based on FeAs alloying, and provides improvement means based on the technical problems that need to be overcome by this new idea:

[0033] A typical arsenic removal method for arsenic-containing crude antimony of the present invention is to directly add an iron-carrying composite material to the crude antimony under an inert atmosphere, and fully stir the melt by gas or mechanical stirring to form a FeAs alloy with the arsenic in the crude antimony and the iron in the composite material. After the stirring is completed, the melt is allowed to stand to allow the formed FeAs-carrying refined slag to float and be separated from the crude antimony melt, thereby achieving efficient arsenic removal from the crude antimony. Specifically, the following steps are included:

[0034] (1) In an inert atmosphere, an iron-loaded composite material is added to a crude antimony melt, and then the molten pool is stirred to perform an arsenic removal reaction; the iron-loaded composite material has a particle size of 1 to 5 mm and a density of less than 3 g / cm 3 The mass of iron in the added iron-bearing composite material is 1 to 2 times the theoretical amount required to transform As into FeAs. The temperature for removing arsenic from crude antimony is 750 to 1000°C.

[0035] (2) After stirring the molten pool for a period of time, the melt is allowed to stand, and then the FeAs-carrying slag on the upper layer of the molten pool is removed to obtain the antimony after arsenic removal.

[0036] A typical embodiment of the present invention is that the iron-loaded composite material is obtained by adding one or a mixture of two of porous carbon, zeolite, and diatomaceous earth as a carrier to a ferrous solution, and chemically reducing or electrochemically reducing ferrous ions to precipitate them in the carrier particles to obtain the iron-loaded composite material.

[0037] In a typical embodiment of the present invention, the stirring of the melt in step (1) can be carried out by gas stirring or mechanical stirring. When gas stirring is adopted, the gas introduced can be nitrogen, argon or other inert gas that does not participate in the reaction.

[0038] A typical embodiment of the present invention is as follows: if the gas stirring method is used in step (1), the time for introducing the gas to react is 1 to 4 hours, and the gas flow rate is 2 to 5 m / t of antimony. 3 / min; if mechanical stirring is used, the reaction time is 1.5-4h, and the melt rotation rate is 10-50rpm.

[0039] In a typical embodiment of the present invention, after the reaction in step (2) is completed, the melt is allowed to stand for 0.5 to 1 hour.

[0040] A typical implementation scheme of the present invention can be listed, and the equipment adapted for this technical scheme is an electric furnace.

[0041] Example 1

[0042] Porous carbon particles with a particle size of 1.5 to 2 mm were added to a 2.5 mol / L ferrous sulfate solution, and 1.0 times the theoretical amount of zinc powder required to reduce all ferrous iron to elemental iron was added to the ferrous sulfate solution, and the reduction reaction was carried out by stirring at 80°C. After a period of reaction, the liquid and solid were separated, washed, dried and sieved to obtain a product with an iron content of 30%, a particle size of 2 mm and a density of 2.80 g / cm 3 The electric furnace was used as the reaction equipment, and the temperature was 800℃ (refining temperature) and N 2 Under the atmosphere, 50 kg of the iron-loaded porous carbon particles were added to 1000 kg of molten crude antimony with an arsenic content of 1.81%; then the melt was fully stirred for 2.5 hours at a speed of 25 rpm using mechanical stirring. After the stirring was completed, the melt was allowed to stand for 0.5 hours to allow the melt to stratify; then the refined slag on the upper layer of the melt was scraped off.

[0043] After arsenic removal, the remaining mass of antimony was 968.33 kg, the arsenic content in antimony was 0.032%, and the direct recovery rate of antimony was 98.59%, which met the arsenic content requirement of Sb 99.70 grade in GB / T 1599-2014.

[0044] Example 2

[0045] Zeolite particles with a particle size of 3 to 4 mm were added to a 2 mol / L ferrous chloride solution, and 1.2 times the theoretical amount of aluminum powder required to reduce all ferrous iron to elemental iron was added to the ferrous chloride solution, and the reduction reaction was carried out by stirring at 50°C. After a period of reaction, the liquid and solid were separated, washed, dried and sieved to obtain a zeolite with an iron content of 25%, a particle size of 4 mm and a density of 2.41 g / cm 3 The iron-loaded zeolite particles were added to 1000 kg of crude antimony melt having an arsenic content of 1.45% at 750°C in an Ar atmosphere using an electric furnace as a reaction device; then 3 m 3 / min, introduce argon into the melt and stir the melt thoroughly for 2h. After stirring, let the melt stand for 0.5h to allow the melt to separate into layers; then remove the refined slag on the upper layer of the melt.

[0046] After arsenic removal, the remaining mass of antimony was 970.08 kg, the arsenic content in antimony was 0.041%, and the direct recovery rate of antimony was 98.39%, which met the arsenic content requirement of Sb 99.70 grade in GB / T 1599-2014.

[0047] Example 3

[0048] Add diatomaceous earth particles with a particle size of 0.5-1.0 mm to a 1.5 mol / L ferrous sulfate solution, add 1.0 times the theoretical amount of aluminum powder required to reduce all ferrous iron to elemental iron to the ferrous sulfate solution, and stir at 60°C for reduction reaction. After a period of reaction, liquid-solid separation, washing, drying and sieving separation, obtain a 10% iron content, 1 mm particle size, and a density of 2.65 g / cm 3 The iron-loaded diatomite particles were heated at 1000℃ and N 2 In the atmosphere, 200 kg of the iron-loaded diatomaceous earth particles were added to 1000 kg of crude antimony melt having an arsenic content of 2.02%; then, 5 m 3 Nitrogen was introduced at a flow rate of 1.25 / min to fully stir the melt for 4 hours. After the ventilation and stirring were completed, the melt was left to stand for 1 hour to allow the melt to stratify; then the refined slag on the upper layer of the melt was scraped off.

[0049] After arsenic removal, the remaining mass of antimony was 936.80 kg, the arsenic content in antimony was 0.024%, and the direct recovery rate of antimony was 95.59%, which met the arsenic content requirement of Sb 99.70 grade in GB / T 1599-2014.

[0050] Example 4

[0051] In a 2.0 mol / L ferrous sulfate solution, diatomaceous earth and porous carbon particles with a particle size of 3 to 4 mm were added, wherein the weight ratio of diatomaceous earth to porous carbon particles was 1:1, and the solution was mechanically stirred at the same time. Graphite was used as an electrode and the current density was 220 A / m 2 The electrolyte was subjected to electrochemical reduction treatment at 35°C for 18 hours, and then the electrolyte was separated into liquid and solid, washed, dried and sieved to obtain a solid with an iron content of 25%, a particle size of 5 mm and a density of 2.64 g / cm 3 The porous carbon and diatomite composite granular material with iron content is prepared. The reaction equipment is an electric furnace at 900℃ and N 2 Under atmosphere, 100 kg of the composite granular material was added into 1000 kg of crude antimony melt with an arsenic content of 2.02%; the melt was fully stirred for 4 hours at a speed of 50 rpm using mechanical stirring. After the stirring was completed, the melt was left to stand for 1 hour to allow the melt to stratify; then the refined slag on the upper layer of the melt was scraped off.

[0052] After arsenic removal, the remaining mass of antimony was 941.98 kg, the arsenic content in antimony was 0.025%, and the direct recovery rate of antimony was 96.12%, which met the arsenic content requirement of Sb 99.70 grade in GB / T 1599-2014.

[0053] Comparative Example 1

[0054] The whole process is the same as Example 1, except that the temperature of the refining process is 1100° C. The experimental results show that after the arsenic removal is completed, the remaining mass of antimony is 996.67 g, the arsenic content in antimony is 1.76%, and the arsenic removal effect is poor.

[0055] Comparative Example 2

[0056] Compared with Example 1, the only difference is that the temperature of the refining process is 700° C. The experimental results show that after arsenic removal, the remaining mass of antimony is 998.4 g, the arsenic content in antimony is 1.94%, no obvious slag layer is seen, resulting in failure to remove slag, and the arsenic removal effect is poor.

[0057] Comparative Example 3 (composite material density is higher than 3g / cm 3 )

[0058] Compared with Example 1, the only difference is that the composite material added to the crude antimony melt during the refining process has an iron content of 40%, a particle size greater than 6 mm, and a density of 3.86 g / cm 3 The amount of iron introduced is the same as in Example 1.

[0059] The experimental results show that after arsenic removal, no obvious slag layer is seen, which makes it impossible to remove the slag. The refined slag and the crude antimony melt are difficult to separate, and arsenic removal cannot be achieved.

[0060] Comparative Example 4

[0061] Compared with Example 1, the only difference is that a small reverberatory furnace is used as the refining equipment in the refining process.

[0062] The experimental results show that after arsenic removal, the remaining mass of antimony is 840.26 kg, the arsenic content in antimony is 0.88%, and the direct recovery rate of antimony is only 84.82%. The direct recovery rate of antimony is low and the arsenic removal effect is poor.

[0063] Comparative Example 4 uses a traditional reverberatory furnace as a refining equipment. The reverberatory furnace provides heat by burning petrochemical energy. To ensure sufficient combustion of the fuel, an oxygen-enriched combustion oxygen supply method is usually adopted, which destroys the inert atmosphere of the alloying arsenic removal reaction. The carbon in part of the composite material is oxidized, the floatability of the alloy phase deteriorates, and the arsenic removal effect deteriorates; antimony is partially oxidized to Sb 2 O 3 Entering the flue gas reduces the direct recovery rate of antimony.

[0064] Comparative Example 5 (Iron is not loaded onto the porous material through a reduction reaction, but the porous material is directly mixed with iron powder)

[0065] Compared with Example 1, the only difference is that the iron in the composite material added to the crude antimony melt during the refining process is not loaded onto the porous carbon through a reduction reaction, but is directly added to the crude antimony melt after mechanically mixing the porous carbon with iron powder (the weight of the introduced porous carbon and iron powder is the same as that of Example 1).

[0066] The experimental results show that after arsenic removal, no obvious slag layer is seen, which makes it impossible to remove the slag. The refined slag and the crude antimony melt are difficult to separate, and arsenic removal cannot be achieved.

Claims

1. A method for removing arsenic from crude antimony containing arsenic, characterized in that: The arsenic-containing crude antimony and the iron-containing composite material are stirred and refined in a protective atmosphere at a temperature of 750-1000° C. to allow As in the arsenic-containing crude antimony and iron in the iron-containing composite material to undergo an alloying reaction and form a slag containing FeAs alloy, which is then skimmed to obtain an arsenic-removed antimony melt; The iron-loaded composite material comprises a carrier and an iron element fixed thereon; Its density is less than 3g / cm 3 , The mass of iron in the added iron-loaded composite material is 1 to 2 times the theoretical amount required to transform As into FeAs.

2. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The arsenic content in the arsenic-containing crude antimony is 0.01-10.0 wt.%.

3. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The iron-loaded composite material is obtained by chemically reducing or electrochemically reducing an iron source to fix it on a carrier; Preferably, the iron source is a ferrous iron and / or ferric iron compound; Preferably, the carrier is at least one of porous carbon, zeolite and diatomaceous earth.

4. The method for removing arsenic from crude antimony containing arsenic as claimed in claim 3, characterized in that Preferably, the iron content in the iron-loaded composite material is 5 to 35 wt.%, preferably 10 to 30 wt.%; Preferably, the particle size of the iron-loaded composite material is 1 to 5 mm; Preferably, the density of the iron-loaded composite material is 1 to 2.5 g / cm 3 .

5. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: A melt containing arsenic and crude antimony is obtained in advance, and then the iron-carrying composite material is added thereto, and refined at the temperature and in the protective atmosphere; Preferably, the mass of iron in the added iron-loaded composite material is 1 to 1.5 times the theoretical amount required to transform As into FeAs.

6. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The heating equipment in the refining stage is an electric furnace.

7. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The temperature in the refining stage is 750-900°C.

8. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The protective gas does not contain any gas that can participate in the reaction, and is preferably at least one of nitrogen and an inert gas.

9. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: The agitation method in the refining stage is gas agitation and / or mechanical agitation; Preferably, the gas used for the gas agitation is a protective gas; Preferably, if the gas stirring method is adopted, the time of introducing the gas into the reaction is 1 to 4 hours, and the gas flow rate is 2 to 5 m / t of antimony. 3 / min input; If mechanical stirring is used, the reaction time is 1.5 to 4 hours, and the melt rotation rate is 10 to 50 rpm.

10. The method for removing arsenic from crude antimony containing arsenic according to claim 1, characterized in that: After the stirring refining is completed, the melt is allowed to stand for 0.5 to 1 hour before slagging.

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