WO2012065406A1

WO2012065406A1 - Method for balancing iron by producing iron vitriol in bio-metallurgy process

Info

Publication number: WO2012065406A1
Application number: PCT/CN2011/073502
Authority: WO
Inventors: 阮仁满; 邹刚; 陈景河; 邹来昌
Original assignee: 紫金矿业集团股份有限公司
Priority date: 2010-11-17
Filing date: 2011-04-29
Publication date: 2012-05-24
Also published as: CN101984095A

Abstract

A method for balancing iron by producing iron vitriol in bio-metallurgy process involves adjusting and optimizing the parameters, such as temperature in the heap,pH in the leaching liquid and the concentration of iron, during the heap bioleaching process of copper sulfide ore containing excess acid iron, so as to form iron vitriol-like substances in the heap to realize the self-balance of ion; employing CaCO₃(lime stone) to neutralize the free acid in raffinate to maintain the pH value of the leaching liquid in the range favoring formation of iron vitriol, so as to realize the balance of iron in the heap bioleaching process. The method can reduce the expense of environmental protection and the cost of production.

Description

Instruction manual

Title: A method for realizing iron balance by using iron sputum in biometallurgical process

[1] The invention relates to a method for realizing iron balance by using iron slag in a biometallurgical process, and is particularly suitable for a copper sulphide ore heap leaching process with high pyrite content and easy excess of acid iron in ore. Background technique

[2] China has a large number of low-grade copper sulfide resources. It is difficult to recover economically and effectively using the traditional fire process with low resource utilization, energy consumption and serious environmental pollution. Copper technology can cost-effectively handle such copper resources.

[3] Low-grade copper ore resources are generally associated with pyrite. During bioleaching, pyrite oxidative exotherm provides sufficient heat for the immersion heap to accelerate the dissolution of copper minerals; while pyrite dissolves to produce large amounts of iron and Sulfuric acid, iron is oxidized into high-iron under the action of microorganisms, and copper minerals can be effectively leached without additional sulfuric acid and high-iron solution during the heap leaching process. However, in some low-grade copper ore heap leaching process with low acid-consuming gangue, the large amount of pyrite dissolved will lead to excessive accumulation of acid iron in the system, resulting in lower extraction electrowinning efficiency, large consumption of extractant, and wastewater treatment. Increased difficulty and other issues.

[4] Most of the traditional processes use lime to neutralize excess acid and iron. The neutralization treatment costs are high, and the resulting stone paste entrains a portion of Cu, and the gypsum adsorbs heavy metal ions as a potential source of secondary solid contamination. The invention provides a novel method for realizing iron balance by using iron shovel generation, only needs to neutralize the free acid in the raffinate, and control pHO. 9-1. 2 , the treatment cost is low, and the generated gypsum is pure and not entrained. Loss of copper, using the existing technical parameters to achieve self-balancing in the heap, greatly reducing the cost of iron neutralization.

Summary of the invention

[5] The object of the present invention is to provide a method for realizing iron balance by using iron shovel in a biometallurgical process, which is simple in process and easy to control in process, and regulates parameters such as temperature in the reactor, pH value of the leaching solution, iron concentration and the like. And reasonable matching, to achieve iron balance in the bio-dip immersion process.

[6] The technical principle of the present invention is: [7] (1) Formation of iron shovel in bio-dip heap

[8] Potassium sulphate (mainly jarosite, yellow sodium iron sulphate, yellow ammonium samarium, scutellaria, etc. also called hydronium ion sputum, etc.) at a suitable temperature, pH, monovalent cation, sulfuric acid Iron concentration and sufficient time can be formed, and the reaction equation is:

[9] R ⁺ +3Fe ₂ (S0 ₄ ) +63⁄40—► 2RFe ₃ (S0 ₄ ) ₂ (OH) ₆ \ +5H ₂ S0 ₄ +4H+

[10] where R stands for K ⁺ , Na\ NH ₄ \ 3⁄40 ⁺

[11] Temperature, pH, iron concentration and time are the main influencing factors of iron sputum formation. A large amount of yellow shovel can be formed in a short time at pH 2. 5 at room temperature, and at a certain temperature at low pH. In order to form, the higher the concentration of ferric sulfate, the easier it is to form jarosite.

[12] In the biopile leaching process, pyrite is oxidized to produce iron and acid and exothermic. Reasonable engineering measures can make the temperature inside the heap greater than 45 °C. The dissolution equation of pyrite under the action of microorganisms is:

Putian

[13] 4FeS ₂ + 150 ₂ + 23⁄40 —► 2Fe ₂ (S0 ₄ ) ₃ + 2H ₂ S0 ₄ +Q

[14] The long-term closed loop of the heap leaching system, the accumulation of acid iron makes the concentration of iron in the leaching solution reach 50g/L or more, and the excess free acid in the system is neutralized, the pH value can be maintained in the range of enthalpy, and a small amount of K ⁺ dissolved in the ore Na ⁺ will give priority to hydrazine, and hydrated hydrogen ions are the main monovalent cations of strontium during bioleaching. Therefore, basic conditions for the formation of stellites are found in the copper sulphide bioleaching reactor.

[15] In the zinc smelting process, the purification of the solution is often carried out by the use of jarosite method. The formation rate of jarosite is the fastest, the iron removal effect is the most thorough, the rate of formation of sassafras is slow, and the solution is in equilibrium. The iron content is still high, which cannot meet the requirements of low iron removal rate and low iron content in the zinc smelting industry. In the biological heap leaching process, the oxidation rate of pyrite is low, and the rate of formation of sassafras is still greater than the dissolution rate of pyrite. Therefore, the self-balancing of iron in the bio-dip heap can be achieved by the formation of iron shovel.

[16] (2) Free acid neutralization and pH control of raffinate

[17] In the biometallurgical bioleaching process, the composition of the solution is complex, containing Cu ₂ ⁺ , Fe ₂ \ Fe ₃ \ S0 ₄ ² — etc., neutralizing the pH of the solution with the neutralization agent calcium carbonate, A high pH will form a Fe(0H) ₃ colloid, which will affect the subsequent extraction electrowinning process. Therefore, the pH should be controlled within a reasonable range. The reaction of the neutralization process is as follows: [18] H ₂ S0 ₄ +CaC0 ₃ →CaS0 ₄ +H ₂ 0+C0 ₂ t

[19] 3Fe ₂ (S0 ₄ ) ₃ + 12H ₂ 0 ^→ 2Fe ₃ (S0 ₄ ) ₂ (0H) · H ₂ 0 I + 5H ₂ S0 ₄

[20] The following relationship exists between the concentration of metal ions and the pH value of the solution and the solubility product of hydroxide:

= _{14 +}丄Igf 丄lg _[M "+]

[21] n n

[22] where: [Mn ⁺ ] - metal ion concentration, mol * Ll;

[23] Ksp-hydroxide solubility product;

[24] n—metal ion valence.

[25] The concentration of Fe ^{3+ in the} leachate of the biolead leaching copper plant is generally lower than 40g/L. The theoretical calculation system produces a minimum pH of 1.58 for Fe(0H) ₃ colloid, and Fe ²⁺ becomes Fe (OH) ₂ precipitated. The initial pH was 7.38, and the 11 precipitated at 01 ²⁺ was 5.01. When the pH of the neutralized iron-rich extract liquid is greater than 1.58, Fe(0H) ₃ colloidal particles are generated in the solution, and Cu ^{2+ is} adsorbed. Therefore, when the raffinate is neutralized by free acid, the pH of the raffinate is controlled to be 0.9-1.5, which avoids the formation of Fe(0H) ₃ colloid and satisfies the vanadium forming condition. DRAWINGS

[26] The specific method of the invention is given by the following figures.

[27] Figure 1 Graph of iron concentration change.

[28] Figure 2 Amplification 20000 times iron strontium crystal scanning electron microscope SEI.

[29] Figure 3 The field exothermic and generated iron sputum.

[30] Figure 4 Zijinshan copper mine leachate and outdoor temperature changes.

[31] Figure 5 Changes in pH and total iron concentration in leachate in the past four years.

detailed description

[32] Example 1:

[33] A low-grade secondary copper sulfide ore heap leaching copper plant raffinate with a composition of Fe ²⁺ 6.23g/L,

TFe47.42g/L, Cu ²⁺ 1.08g/L, S0 ₄ ² "171g/L, K+20mg/L, pH 1.2. Take 300ml of raffinate in a 500ml Erlenmeyer flask on a 60°C water bath shaker. After shaking for 40 days, the concentration of TFe in the solution dropped to 41g/L (shown in Figure 1), and the concentration of S0 ₄ ² - decreased to 154g/L. A yellow precipitate appeared on the bottom of the bottle and was identified as a mixture of iron sputum by XRD. For the yellow sorghum and jarosite, Figure 2 is a scanning electron microscope image. The test results show that the raffinate is at the right temperature, acidity and iron concentration. It can produce stable iron sputum substances.

[34] Example 2:

[35] During the bioleaching shake flask test of a copper sulfide containing 0.4% copper, the other components of the ore were S5.28%, Fe3.59%, K ₂ 01.58%, and the ore was ground to a particle size of -0.074 mm. After 90%, the shake flask leaching test was carried out. The slurry concentration was 5%, the temperature was 30, 45, 60 °C. During the test, the pH was controlled at 0.9-1.2, the leaching time was 15 days, and the leaching agent composition was as shown in Table 1.

[36] Table 1 Raffinate element composition g/L

[37] After the test, Cu, Fe, Al, and the dissolution rate of pyrite in the ore were detected by MLA. The test results are shown in Table 2.

[38] Table 2 Copper ore leaching

[39] The test results show that the temperature is positively correlated with copper leaching. The pyrite dissolution rate and iron dissolution rate are equivalent at 30 °C, which proves that iron bismuth is not formed under this condition; the pyrite dissolution rate is 33.2% at 45 °C. It is greater than the iron dissolution rate of 10.3%, indicating that 23% of the iron is transferred into the slag; the pyrite dissolution rate is 44.8% at 60 °C, and the iron dissolution rate is -17.69%, which proves that not only the iron dissolved by the pyrite is transferred. In the solid phase, some of the iron in the solution is transferred to the slag. Therefore, under suitable conditions, the copper sulfide ore can be leached into the solid phase by the formation of an iron sputum.

[40] Example 3:

[41] A large-scale secondary copper sulfide ore with low arsenic content in China. The main metal minerals are pyrite, lanhui copper, copper blue, etc., which are closely symbiotic. Due to the low grade, the traditional fire smelting process is developed, the investment is large, the economic benefit is poor, and the bio-pile leaching copper process is developed and applied. The mine can be used efficiently, the copper leaching rate reaches 80%, and the cost per ton of copper is only 16500 yuan. . Ore crushed to particle size After -60mm, the layer-by-layer stacking method is adopted, and the stack height is controlled by 25m, and intermittent spraying is adopted. The oxidative exotherm of pyrite in the ore causes the temperature of the leachate to be between 45-55 ° C (Fig. 3, 4), thus presuming that the temperature in the stack is greater than 45 ° C, and the temperature in the stack is as high as 75 ° C.

[42] Due to the continuous oxidation of pyrite in the ore and the accumulation of acid iron in the closed loop of the leachate, the iron concentration accumulated to 50g/L at the end of 2007, and the pH of the solution was as low as 0.85 (Fig. 5). The continuous accumulation of ferric acid will affect Subsequent extraction of the electrowinning process. In July 2008, the limestone neutralization raffinate was used to control the pH of the solution to 0.92 (Fig. 5), which satisfied the vanadium forming conditions and produced a large amount of iron strontium in the heap (Fig. 3). After this method, the TFe concentration in the solution was stabilized at 50-60 g/L (Fig. 5), and the system iron balance was achieved.

Industrial applicability

[43] The method for realizing iron balance by using iron slag in a biometallurgical process, is applicable to a copper sulphide ore bioleaching process with low copper-sulfur ratio, high pyrite content and less acid-consuming gangue, which can be solved The problem of excess acid iron in the system makes the bioleaching-extraction-electro-accumulation system in a virtuous cycle, reducing environmental protection treatment costs and reducing production costs.

Claims

Claim

[Claim 1] A method for realizing iron balance by using iron sputum in a biometallurgical process, characterized in that: in the process of biolead leaching of copper sulphide ore, by regulating the temperature inside the heap, the pH of the leaching solution, and the iron Concentration and other parameters are matched reasonably, and iron-like substances are formed in the heap to achieve self-balancing of iron. By neutralizing the free acid of the raffinate, the pH value of the leachate is maintained in the range of iron shovel formation, and low-cost iron balance is achieved.

[Claim 2] A method for achieving iron balance by using iron slag generation in a biometallurgical process according to claim 1, wherein: the temperature in the bioimmersion reactor is controlled to be greater than 45 °C.

[Claim 3] A method for realizing iron balance by using iron sputum in a biometallurgical process according to claim 1, wherein: the raffinate free acid neutralizing agent is calcium carbonate, and the pH of the raffinate is controlled. 0. 9-1. 2, after the raffinate is neutralized and concentrated by the neutralizing agent, the supernatant is pumped to the stack spraying process for recycling, and the underlying solid sediment is sent to the tailings storage.

[Claim 4] A method for realizing iron balance by using iron sputum in a biometallurgical process according to claim 1, wherein: in the biometallurgical biological heap leaching process, the total iron concentration of the leaching solution is stable at 40-60 g /L.

[Claim 5] The method for realizing iron balance by using iron sputum in a biometallurgical process according to claim 1 or 2 or 3 or 4, wherein: the excess iron sulfide ore of the acid iron is contained Low-grade arsenic large-scale secondary copper sulfide ore, the main metal minerals are pyrite, lanhui copper ore, copper blue.

[Claim 6] A method for realizing iron balance by using iron shovel in a biometallurgical process according to claim 5, wherein the ore is crushed to a particle size of -60 mm After that, the layer-by-layer stacking method is adopted, the stacking height is controlled by 25m, and the intermittent spraying method is adopted, and the temperature of the leachate is between 45-55 °C.