CN100488890C - Method for reclaiming valuable element from acidic arsenic-containing biological oxidation gold extraction waste liquor - Google Patents

Abstract

A method for recovering valuable elements from acidic arsenic-containing bio-oxidation gold extraction waste liquid, simultaneously adding acidic arsenic-containing bio-oxidation gold extraction waste liquid and a precipitant to the reaction kettle, and realizing the separation of arsenic and iron through selective precipitation; Filtration technology realizes solid-liquid separation, the solid phase enters the iron red preparation process, and the liquid enters the arsenic recovery process; after the arsenic recovery, the solution is adjusted to neutrality with lye, and Na ₂ SO ₄ ·10H ₂ O is condensed and crystallized at 0-4°C ; The tail liquid after recovering Na ₂ SO ₄ ·10H ₂ O is returned to the first step to prepare the alkali solution. Beneficial effects of the present invention: realize effective separation of arsenic and iron from acidic arsenic-containing biooxidation gold extraction waste liquid, and separate recycling of arsenic, iron, and sulfur, zero discharge in the whole process, and no secondary pollution; acidic arsenic-containing biooxidation gold extraction waste The liquid realizes harmless and resource-based comprehensive treatment.

Description

Method for recovering valuable elements from acidic arsenic-containing biological oxidation gold extraction waste liquid

technical field

The invention relates to a technology for extracting valuable elements from acidic arsenic-containing biological oxidation gold extraction waste liquid.

Background technique

At present, there are many domestic production plants using bio-oxidation gold extraction technology, becoming the country with the most bio-oxidation gold extraction plants in the world.

However, a large amount of arsenic-containing acidic bio-oxidation gold-extraction waste liquid is produced in the bio-oxidation gold extraction process. The pH value of this type of biological oxidation liquid is 0.6 to ^1.8 . Contains (25-45) kg of iron and about 8 kg of arsenic and a small amount of elements such as copper, zinc, and lead. Arsenic compounds are protoplasmic poisons with a wide range of biological effects, and have been identified as the first class of carcinogens by the International Agency for Cancer Research.

At present, the more successful method for treating acidic arsenic-containing bio-oxidation gold extraction waste liquid is the "lime-iron salt method", that is, under the condition of Fe/As greater than 3, neutralize with lime, so that As can form a relatively stable FeAsO ₄ precipitation Remove from solution. However, there is still Fe ²⁺ in the gold extraction waste of the biological oxidation solution, so that the arsenic in the "neutralization slag" cannot completely exist as FeAsO ₄ , but partly exists in the form of Ca(AsO ₃ ) ₂ . The solubility of this kind of arsenic-containing salt increases with the change of soil conditions and the action of bacteria, which will cause obvious secondary pollution. More importantly, when using the "lime-iron-salt neutralization precipitation method" for harmless treatment, a large amount of lime needs to be consumed. 1 ton of gold concentrate consumes 300-400Kg of lime. If 100 tons of gold concentrate is processed daily, the resulting When bio-oxidation gold extraction waste liquid is harmlessly treated by "lime iron salt method", it needs to consume 30-40 tons of lime per day and produce about 120 tons of neutralized slag, so about 40,000 tons of neutralized slag will be produced every year. And slag, such a large amount of slag, Sinotrans will consume a lot of manpower and financial resources, and increase the cost of gold production. In addition, these arsenic-containing neutralized slags are placed in the tailings pool, which is also a potential source of pollution. At the same time, valuable elements such as arsenic, iron and sulfur in the acidic arsenic-containing biological oxidation gold extraction waste liquid are thrown away in vain. The bio-oxidation gold extraction plant that processes 100 tons of gold concentrate daily discharges 500-600m ³ of acidic bio-oxidation gold extraction waste liquid, and throws away nearly 1400-1700 tons of arsenic and 4000-8000 tons of iron every year, resulting in a great waste of resources . To recover these valuable elements and make them into high value-added products will produce considerable economic benefits.

Contents of the invention

Aiming at the deficiencies of the existing acidic bio-oxidation gold extraction waste liquid treatment technology, the present invention provides a method for recovering valuable elements from the acidic arsenic-containing bio-oxidation gold extraction waste liquid based on chemical methods and supplemented by external field effects , the method can make the acidic arsenic-containing biological oxidation gold extraction waste liquid harmless, and realize the comprehensive utilization of resources and zero discharge in the gold production process, reduce the gold production cost, and improve economic benefits.

In order to solve the technical problem of acidic biological oxidation gold extraction waste liquid treatment, the technical scheme adopted is: the acidic arsenic-containing biological oxidation gold extraction waste liquid is used as the treatment object, and the waste liquid contains Fe, As, Zn, Cu, Pb, S and other elements, the contents of which are 25~45g·L ^-1 Fe, 2~9g·L ^-1 As, 0.1~0.3g·L ^-1 Zn, 0.01~0.07g·L ^-1 Cu, 0.02~0.03g ·L ^-1 Pb, 12～30g·L ^-1 S, in which sulfur and arsenic exist in the form of sulfate and arsenate respectively, most of iron exists in the form of Fe ³⁺ , and the pH value of bio-oxidation gold extraction waste liquid is 0.6～1.8 .

In view of the above conditions, the process of extracting valuable elements is:

1. At the same time, add acidic arsenic-containing biological oxidation gold extraction waste liquid and precipitant to the reactor. The precipitant can be 6-10mol·L ^-1 alkali solution or urea. The pH value of the system in the reactor is 9 ～14. Under the conditions of reaction temperature 10～60℃ and stirring intensity 600～800r/min, the separation of arsenic and iron can be realized through selective precipitation;

If NaOH is used as precipitant, the main reaction is Fe ³⁺ +3(OH ^-1 )=Fe(OH) ₃ ↓

2. After solid-liquid separation is achieved by filtration or centrifugal separation, the solid phase enters the iron red preparation process, and the liquid enters the arsenic recovery process;

3. After the iron precipitate is washed with water, it is roasted in the air atmosphere for 1-2 hours (temperature range 500-900°C) to obtain iron red;

4. At the same time, add arsenic-containing liquid with a concentration of 1 to 2 mol·L ^-1 sodium sulfide solution and a concentration of 3 ^to 4 mol·L 0.5~3, the stirring intensity is 300~500r/min, the magnetic field strength is 0.2~0.5T or no magnetic field is added, the arsenic is recovered through sulfidation precipitation reaction, and the primary product can be realgar or orpiment; further, it can be reduced by wet method Preparation of elemental arsenic;

5. The solution after recovering arsenic is adjusted to neutrality with 4mol L ^-1 NaOH solution, and Na ₂ SO ₄ 10H ₂ O is condensed and crystallized at 0-4°C;

6. The tail liquid after recovering Na ₂ SO ₄ is returned to the first step to prepare the alkali solution to achieve zero discharge in the whole process.

The beneficial effects of the present invention are:

1. Realize the effective separation of arsenic and iron from acidic arsenic-containing biological oxidation gold extraction waste liquid and the separate recycling of arsenic, iron and sulfur. The recovery rates of arsenic, iron and sulfur are all above 96%;

2. Zero discharge in the whole process, no secondary pollution;

3. The acidic arsenic-containing biological oxidation gold extraction waste liquid realizes harmless and resource-based comprehensive treatment, which makes the process of "biological oxidation gold extraction technology" more perfect. Avoid the shortcomings of the original process of "lime iron salt method" in the treatment of acidic arsenic-containing biological oxidation gold extraction waste liquid, such as large lime consumption, large amount of slag, potential pollution sources, and waste of resources caused by valuable elements being thrown away in vain.

Description of drawings

Fig. 1 is a process flow diagram for extracting valuable elements from acidic arsenic-containing biological oxidation gold extraction waste liquid;

Detailed ways

example 1

1. Taking the treatment of 250m ³ bio-oxidation gold extraction waste liquid every day (the main element Fe content is 24g/L, As content is 5g/L) as an example, the recovery process of its valuable elements is: alkali is used as a medicament, and 8mol· L ^-1 alkaline solution is used as a precipitant, and at the same time, add acidic arsenic-containing bio-oxidation gold extraction waste liquid and a precipitant to the reactor, adjust the flow rate of the biological oxidation solution to 10.5m ³ /h, and the flow rate of the precipitant to about 5.6m ³ / h, and subject to controlling pH=12.5 in the reactor, adjust the flow rate of the precipitant at any time, the reaction temperature is 10°C, and the stirring intensity is 500rpm/min to separate arsenic and iron;

2. Use filtration or centrifugal separation technology to separate solid and liquid, the solid phase enters the iron red preparation process, and the arsenic-containing liquid enters the arsenic recovery process;

3. After the solid phase precipitate is washed and dried with water, it is roasted in an air atmosphere at 500°C for 1 hour to obtain iron red;

4. The obtained arsenic-containing liquid enters the arsenic recovery process. The three liquids including the arsenic-containing liquid, sulfuric acid with a concentration of 3mol L ^-1 and sodium sulfide with a concentration of 1mol L ^-1 are simultaneously added to the arsenic-precipitation reaction kettle. The basic flow rate is 15m ³ /h, the flow rate ratio of arsenic-containing liquid: concentrated sulfuric acid: sodium sulfide is controlled as 10:1:1, the flow rate of sulfuric acid solution is adjusted appropriately, the pH in the reaction system is controlled to be 0.5~1, and the stirring intensity is 300r/min , the magnetic field strength is 0.2T or no magnetic field is added, carry out sulfidation precipitation, the liquid flowing out from the reaction kettle is separated by solid-liquid, arsenic is recovered with sulfide, and the primary product obtained at this time is realgar or orpiment;

5. Add 4 mol·L ^-1 NaOH solution to the recovered arsenic solution, adjust to neutral, condense and crystallize at 0°C for 2 hours to obtain Na ₂ SO ₄ ·10H ₂ O, and then heat to obtain anhydrous sodium sulfate;

6. The tail liquid after recovering Na ₂ SO ₄ is returned to the first step to prepare the alkali solution to achieve zero discharge in the whole process.

Example 2

1. Taking the treatment of 500m ³ bio-oxidation gold extraction waste liquid every day (the main element Fe content is 36g/L, As content is 7.5g/L) as an example, the recovery process of its valuable elements is: alkali is used as a drug, and 10mol ·L ^-1 alkaline solution is used as precipitant, and acid arsenic-containing biological oxidation gold extraction waste liquid and precipitant are added to the reactor at the same time, and the flow rate of biological oxidation solution is adjusted to 21m ³ /h, and the flow rate of precipitant is about 11m ³ /h , and based on the control of pH=13.5 in the reactor, adjust the flow rate of the precipitant at any time, the reaction temperature is 40°C, and the stirring intensity is 700rpm/min for the separation of arsenic and iron;

2. Use filtration or centrifugal separation technology to separate solid and liquid, the solid phase enters the iron red preparation process, and the arsenic-containing liquid enters the arsenic recovery process;

3. After the solid-phase precipitate is washed and dried, it is roasted in an air atmosphere at 700°C for 1 hour to obtain iron red;

4. The obtained arsenic-containing liquid enters the arsenic recovery process, and the three liquids including the arsenic-containing liquid, sulfuric acid with a concentration of 3.5 mol L ^-1 and sodium sulfide with a concentration of 1.5 mol ^L The basic flow rate of arsenic liquid is 25m ³ /h, the flow rate ratio of arsenic liquid:concentrated sulfuric acid:sodium sulfide is controlled as 10:1:1.1, the flow rate of sulfuric acid liquid is adjusted appropriately, the pH in the reaction system is controlled to be 1~2, and the stirring intensity is 400r /min, magnetic field intensity 0.3T or no magnetic field, carry out sulfide precipitation, the liquid flowing out from the reactor is separated by solid-liquid, arsenic is recovered with sulfide, and the primary product obtained at this time is realgar or orpiment;

5. Add 4mol·L ^-1 NaOH solution to the recovered arsenic solution, adjust to neutral, condense and crystallize at 2°C for 2 hours to obtain Na ₂ SO ₄ ·10H ₂ O, and then heat to obtain anhydrous sodium sulfate;

6. The tail liquid after recovering Na ₂ SO ₄ is returned to the first step to prepare the alkali solution to achieve zero discharge in the whole process.

Example 3

Take the treatment of 500m ³ biological oxidation waste liquid every day (the main element Fe content is 45g/L, As content is 8.5g/L) as an example. The recovery process of the valuable elements is as follows: the alkali is used as the medicine, and a 10mol·L ^-1 alkali solution is prepared as the precipitating agent. At the same time, add acidic arsenic-containing biological oxidation gold extraction waste liquid and precipitant to the reactor, adjust the flow rate of biological oxidation solution to be 21m ³ /h, and the flow rate of precipitant to be about 12m ³ /h, and control the pH in the reactor to be 13.5 Accurate, adjust the flow rate of the precipitant at any time, the reaction temperature is 60°C, the stirring intensity is 800rpm/min, and the arsenic and iron are separated;

2. Use filtration or centrifugal separation technology to separate solid and liquid, the solid phase enters the iron red preparation process, and the arsenic-containing liquid enters the arsenic recovery process;

3. After the solid-phase precipitate is washed and dried, it is roasted in an air atmosphere at 900°C for 2 hours to obtain iron red;

4. The obtained arsenic-containing liquid enters the arsenic recovery process, and the three liquids including the arsenic-containing liquid, sulfuric acid with a concentration of 4mol L ^-1 and sodium sulfide with a concentration of 2mol L ^-1 are simultaneously added to the sulfide arsenic precipitation reactor, and the arsenic-containing liquid The basic flow rate is 31m ³ /h, the flow rate ratio of arsenic-containing liquid: concentrated sulfuric acid: sodium sulfide is controlled as 10:1:1.2, the flow rate of sulfuric acid solution is adjusted appropriately, the pH in the reaction system is controlled to be 2~3, and the stirring intensity is 500r/min , The magnetic field strength is 0.5T or no magnetic field is applied for sulfuration precipitation. The liquid flowing out from the reaction kettle is separated from the solid and liquid, and the arsenic is recovered as sulfide, and the primary product obtained at this time is realgar or orpiment;

5. Add 4 mol·L ^-1 NaOH solution to the solution after recovery of arsenic, adjust to neutral, condense and crystallize at 4°C for 2 hours to obtain Na ₂ SO ₄ ·10H ₂ O, and then heat to obtain anhydrous sodium sulfate;

6. The tail liquid after recovering Na ₂ SO ₄ is returned to the first step to prepare the alkali solution to achieve zero discharge in the whole process.

Claims (1)

1, a kind of method that reclaims valuable element from acidic arsenic-containing biological oxidation gold extraction waste liquor is characterized in that may further comprise the steps:

1) add acidic arsenic-containing biological oxidation gold extraction waste liquor and precipitation agent, simultaneously in reactor, this precipitation agent is 6～10molL ^-1Alkaline solution or urea, system pH is 9～14 in the control reactor, temperature of reaction is 10～60 ℃, at stirring intensity be under the condition of 600～800r/min by selective precipitation, realize that arsenic iron separates;

2), adopt to filter or centrifugal separation technique is realized solid-liquid separation, separate the back solid phase and enter the iron oxide red preparation section, liquid enters the operation that reclaims arsenic;

3), iron precipitate roasting 1～2 hour in air atmosphere after washing, maturing temperature is 500～900 ℃, obtains iron oxide red;

4), in the heavy arsenic reactor of sulfuration, add simultaneously through after the solid-liquid separation contain arsenic liquid, concentration is 1～2molL ^-1Sodium sulfide solution and concentration are 3～4molL ^-1Sulphuric acid soln is 0.5～3 in the pH value, stirring intensity is that 300～500r/min, magneticstrength are 0.2～0.5T or do not add under the condition in magnetic field, reclaims arsenic by the sulfide precipitation reaction, and primary products are realgar or orpiment; In order to further passing through wet reducing prepared in reaction elemental arsenic;

5), the solution behind the recovery arsenic is with 4molL ^-1NaOH solution transfer to neutrality, 0～4 ℃ of condensation-crystallization goes out Na ₂SO ₄10H ₂O;

6), reclaim Na ₂SO ₄After tail washings return the 1st step operation, in order to the preparation alkaline solution, realize the whole process zero release.

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