CN106636678B - A kind of method that arsenic-containing material direct-reduction roasting prepares arsenic - Google Patents

Abstract

The invention discloses a method for preparing arsenic by directly reducing and roasting arsenic-containing materials. The method uses arsenate as a raw material, and after the arsenate material is uniformly mixed with a carbonaceous reducing agent, it is placed in an inert or reducing atmosphere, and the Under certain conditions, reduction roasting is carried out, and roasting flue gas is collected to obtain arsenic products. This method reduces the common arsenate-containing arsenic materials in the metallurgical process to chemically stable elemental arsenic. Elemental arsenic is not only non-toxic but also can be used as a raw material for semiconductor and alloy industries, and has certain market value. The reduction process realizes It is the most reasonable direction for arsenic to realize the reduction, harmlessness and recycling of toxic arsenic-containing materials, and it is of great promotion value.

Description

A method for preparing arsenic by directly reducing and roasting arsenic-containing materials

technical field

The invention relates to a method for preparing arsenic from arsenic-containing materials, in particular to a method for directly preparing arsenic from arsenic-containing materials through reduction roasting, and belongs to the technical field of nonferrous metal metallurgy.

technical background

The alkali slag, soot and anode slime produced in the non-ferrous smelting process often contain arsenic. When the wet process is used for treatment and purification, the arsenic removal process is essential. Leaching under alkaline conditions, followed by crystallization or precipitation separation is an effective and common method for arsenic removal, but this process produces a large amount of arsenate, which is toxic and chemically unstable, and is likely to be harmful to the environment and human health. posed a threat, it was therefore necessary to find an economical and environmentally friendly method for subsequent disposal of arsenate.

For the treatment of this kind of arsenate, the method of solidification is mainly adopted at present. The common solidification methods include cement solidification, lime solidification, plastic solidification, asphalt solidification, melt solidification, etc. Although arsenic can be fixed to a certain extent, these The curing methods all have the problems of large volume increase ratio before and after curing, and the need for a large amount of land stockpiling and landfilling in the later stage.

At present, the production of metal arsenic is generally obtained by oxidizing and roasting arsenic-containing ores first to recover arsenic oxides, and then using arsenic oxides as raw materials, and using hydrogen, carbon, etc. as reducing agents to carry out reduction reactions. A report on the direct reduction of arsenate.

Contents of the invention

In order to solve the difficult problem of existing arsenic-containing materials, especially arsenate materials, the purpose of the present invention is to provide a clean and efficient method for directly recovering high-purity arsenic from arsenic-containing materials, which realizes Reduction, harmlessness and recycling of arsenic-containing waste residues.

In order to achieve the above technical purpose, the present invention provides a method for preparing arsenic by direct reduction and roasting of arsenic-containing materials. After the arsenate material is mixed with a carbonaceous reducing agent, it is placed in an inert or reducing atmosphere. Reduction roasting is carried out under temperature conditions, and roasting flue gas is collected to obtain arsenic products.

In a preferred solution, the ratio of the arsenate material to the carbonaceous reducing agent is measured by a molar ratio of arsenic to carbon of 1:(0.5-5).

More preferably, the arsenate material includes at least one of sodium arsenate, calcium arsenate, lead arsenate, barium arsenate, magnesium arsenate and iron arsenate.

More preferably, the carbonaceous reducing agent includes at least one of petroleum tar powder, coke powder, activated carbon powder, carbon black powder, graphite powder and charcoal powder.

In a preferred solution, the vacuum degree of the negative pressure is 0.1-101325Pa.

In a preferred solution, the reduction calcination temperature is more preferably 700-1200°C, and more preferably the reduction calcination temperature is 700-900°C.

In a preferred scheme, the reduction roasting time is 1-8 hours; the more preferred reduction roasting time is 2-4 hours.

In a preferred solution, the grade of the arsenic product is greater than 90%; more preferably, the grade is greater than 94%.

The reducing atmosphere adopted in the technical solution of the present invention is mainly a mixed atmosphere of inert gas and/or nitrogen and hydrogen and/or carbon monoxide.

The basic principle of the technical solution of the present invention, and the advantage brought compared with the prior art:

The key to the technical solution of the present invention is the control of conditions such as temperature and pressure in the reduction roasting. A large number of studies by the inventor have shown that under the conditions controlled by the technical solution of the present invention, the arsenate material mainly occurs in the carbonaceous reducing agent. The following reduction reactions are specifically illustrated by taking sodium arsenate, calcium arsenate and iron arsenate as examples, and the reactions that occur are shown in equations (1) to (7):

4Na ₃ AsO ₄ +5C＝5Na ₂ CO ₃ +As ₄ (g)+Na ₂ O (1)

4Na ₃ AsO ₄ +5C+H ₂ O=5Na ₂ CO ₃ +As ₄ (g)+2NaOH (2)

4Na ₃ AsO ₄ +10C+6H ₂ O(g)=12NaOH+10CO(g)+As ₄ (g) (3)

2Ca ₃ (AsO ₄ ) ₂ +5C＝6CaO+5CO ₂ (g)+As ₄ (g) (4)

2Ca ₃ (AsO ₄ ) ₂ +10C＝6CaO+10CO(g)+As ₄ (g) (5)

4FeAsO ₄ +8C＝4Fe+8CO ₂ (g)+As ₄ (g) (6)

4FeAsO ₄ +16C＝4Fe+16CO(g)+As ₄ (g) (7)

The relationship between the change value of Gibbs free energy and temperature of reactions (1)-(7) is shown in Figure 1. As can be seen from Figure 1, under the process conditions of the present invention, these reactions can all take place smoothly.

Compared with prior art, the beneficial effect of the present invention is:

1) In the technical solution of the present invention, the arsenate material is reduced in one step to prepare a high-purity arsenic product for the first time by a reduction roasting method.

2) Through the technical solution of the present invention, the toxic arsenate that exists in large quantities in the existing nonferrous metallurgy industry can be reduced to non-toxic elemental arsenic, the yield of arsenic is >95%, the purity of elemental arsenic is >90%, and it can be directly sold as a product At the same time, the volume of arsenic-containing substances before and after the reaction is reduced, which is beneficial to landfill and stockpiling disposal; the reduction, harmless and resourceful disposal of arsenic has been realized, and it has promotion value.

3) The technical solution of the present invention has mild process conditions, environmental protection, simple operation, and is beneficial to industrialized production.

Description of drawings

[Figure 1] is the relationship between the change of Gibbs free energy and temperature for reactions (1)-(7) under normal pressure conditions;

Detailed ways

The content of the present invention will be further described below in conjunction with specific examples, but the protection scope of the claims of the present invention will not be limited.

Example 1

Using calcium arsenate obtained from a certain copper soot alkali leaching-lime precipitation in Yunnan as raw material, take 100Kg of the raw material and mix it with carbon powder evenly and put it into a vacuum electric arc furnace (the amount of carbon powder added is 15% of the mass of the raw material), turn on the vacuum pump, when the pressure Start to heat up at 1000Pa, raise the temperature to 700°C and maintain the reducing environment for 3 hours, then stop heating to condense the arsenic vapor. After the reduction is completed, when the temperature drops to room temperature, close the vacuum furnace, and obtain metal arsenic from the condensation pipe section, the purity of which is >95 %, the main component of the reduced slag sample is CaO.

Example 2

Sodium arsenate crystals obtained by high-pressure alkali leaching-cooling crystallization of a tin electrolytic anode slime in Yunnan are used as raw materials. The crystals contain 30.13% As, 0.58% Pb, 0.42% Sb and 0.07% Sn. Take 100Kg of the sodium arsenate crystal and mix it with carbon powder and put it into a vacuum electric arc furnace (the amount of carbon powder added is 20% of the mass of the raw material), turn on the vacuum pump, start to heat up when the pressure is 1Pa, and raise the temperature to 700°C and maintain a reducing environment for 4 After 1 hour, stop heating to condense the arsenic vapor. After the reduction, when the temperature drops to room temperature, close the vacuum furnace, and obtain metallic arsenic from the condensation pipe section. The purity is >94% after testing. The main component of the reduction slag sample is Na ₂ CO ₃ .

Example 3

With the ferric arsenate obtained by high-pressure alkali leaching-iron salt precipitation of a certain copper electrolytic anode slime in Yunnan as raw material, 100Kg of raw material and carbon powder are mixed evenly and then put into a reduction electric furnace (the carbon powder addition is 20% of the raw material quality), and the temperature is raised to Keep the reducing environment at 900°C for 2 hours, then stop heating to condense the arsenic vapor. After the reduction, when the temperature drops to room temperature, close the reduction furnace, and obtain metallic arsenic from the condensation pipe section. The purity is >96% after testing, and the main components of the reduced slag sample It is an oxide of Fe.

Comparative Example 1

Sodium arsenate crystals obtained by high-pressure alkali leaching-cooling crystallization of a tin electrolytic anode slime in Yunnan are used as raw materials. The crystals contain 30.13% As, 0.58% Pb, 0.42% Sb and 0.07% Sn. Take 100Kg of the sodium arsenate crystal and mix it evenly with carbon powder and put it into a vacuum electric arc furnace (the amount of carbon powder added is 20% of the mass of the raw material), turn on the vacuum pump, start to heat up when the pressure is 1Pa, raise the temperature to 550 ° C and maintain a reducing environment for 4 Stop heating after 1 hour, arsenic mainly exists in the reducing slag sample in the form of elemental substance and sodium arsenate, and metal arsenic is hardly obtained in the condensation pipe section.

Claims (6)

1. a kind of method that arsenic-containing material direct-reduction roasting prepares arsenic, it is characterised in that：Arsenate material and carbonaceous reducing agent It after mixing, is placed in inertia or reducing atmosphere, reduction roasting is carried out under negative pressure and >=600 DEG C of temperature conditions, collect roasting cigarette Gas is to get arsenic product；

The ratio of the arsenate material and the carbonaceous reducing agent is with the molar ratio of arsenic and carbon for 1:(0.5~5) it measures.

2. the method that arsenic-containing material direct-reduction roasting according to claim 1 prepares arsenic, it is characterised in that：The arsenic Aluminate materials include at least one of natrium arsenicum, calcium arsenate, lead arsenate, barium arsenate, magnesium arsenate, ferric arsenate.

3. the method that arsenic-containing material direct-reduction roasting according to claim 1 prepares arsenic, it is characterised in that：The carbon Matter reducing agent includes at least one of stone tar powder, coke blacking, active powdered carbon, carbon black powder, graphite powder and charcoal powder.

4. the method that arsenic-containing material direct-reduction roasting according to claim 1 prepares arsenic, it is characterised in that：The negative pressure Vacuum degree be 0.1~101325Pa.

5. the method that arsenic-containing material direct-reduction roasting according to claim 1 prepares arsenic, it is characterised in that：Described goes back Former roasting time is 1~8h.

6. the method that arsenic-containing material direct-reduction roasting according to claim 1 prepares arsenic, it is characterised in that：The arsenic Product grade is more than 90%.