CN114574713B - Method for separating iron and nickel and cobalt from nickel and cobalt acid leaching solution containing high-concentration iron ions - Google Patents

Abstract

The invention belongs to the field of hydrometallurgy, and particularly relates to a method for separating iron and nickel cobalt from nickel cobalt acid leachate containing high-concentration iron ions, wherein a phosphate source and a phosphorus-containing auxiliary agent are added into a solution to be treated containing iron ions, nickel ions and cobalt ions, the solution is reacted at the temperature of 10-50 ℃ and the pH value of 1.4-1.9, and then solid-liquid separation is carried out to obtain an iron phosphate product and a reaction liquid enriched with nickel cobalt. In the invention, under the combined control of the phosphate source, the phosphorus-containing auxiliary agent and the components, the combined control of the reaction temperature and the pH is further matched, so that the synergy can be realized, the problems of non-ideal separation selectivity and separation efficiency of iron and nickel cobalt caused by high iron concentration can be effectively solved, the recovery rate of iron in single-stage reaction can be obviously improved, the loss of nickel and cobalt can be reduced, the separation selectivity of iron and nickel and cobalt can be obviously improved, and the reaction efficiency can be improved.

Description

Method for separating iron and nickel and cobalt from nickel and cobalt acid leaching solution containing high-concentration iron ions

Technical Field

The invention discloses a method for separating iron and nickel and cobalt from nickel and cobalt acid leachate containing high-concentration iron ions, and belongs to the technical field of hydrometallurgy.

Background

Lithium ion batteries have the advantages of high specific energy, high battery voltage, wide working temperature range, long storage life and the like, and are widely applied. In recent years, new energy automobile industrialization is promoted worldwide, and the demand of lithium ion power batteries is greatly improved. Our country is the largest power battery market worldwide, with demand estimated at 325GWh in 2022, accounting for approximately 80% of the total market volume. Lithium ion batteries are mainly classified into lithium iron phosphate batteries and ternary lithium batteries, wherein the proportion of the ternary lithium batteries (such as nickel-cobalt-manganese ternary lithium batteries) is about 60%. And as the ternary cathode material is continuously developed to high nickel (such as NCM 811), the demand of nickel and cobalt for the battery is continuously increased. The amount of metals in the battery is about 18 ten thousand tons in the world in 2019, and the demand is estimated to reach about 90 ten thousand tons in 2030. The power battery will become the second largest consumer area for nickel following stainless steel.

The laterite nickel ore is a main mineral for extracting nickel and cobalt, pure nickel (such as nickel plate) or nickel salt (such as nickel hydroxide and nickel sulfate) can be prepared by hydrometallurgy, not only can the comprehensive recovery of nickel and cobalt be realized, but also the prepared product is suitable for further processing into a nickel-based battery. The high-pressure acid leaching method is a hydrometallurgical process for treating laterite nickel ore at present in commercial use. The high-pressure acid leaching process is adopted by a plurality of nickel-cobalt production enterprises such as Guba MOA, australia Murrin Murririn and the like in sequence. With the continuous expansion of the demand of nickel for batteries, domestic related enterprises are built or planned to build high-pressure acid leaching production lines. For example, the production line of 35000 tons of nickel metal and 3400 tons of cobalt metal per year has been built by Midamia group in Babuya New Guinea Renau, and the high-nickel ternary precursor production line of 6 ten thousand tons is additionally built in Caofei Dian in 2018; in 2019, smelting projects with the nickel metal amount of 5 ten thousand tons and the cobalt metal amount of 4000 tons are produced in construction years of Indonesia, such as Qingshan, green forest and the like; cobalt, hua Youyou, etc. will produce 6 million tons of nickel metal items in the Co-construction year in Indonesia; hey yi latitude lithium energy, etc. will produce a production line of about 12 million tons of nickel metal and 1.5 million tons of cobalt metal in the construction year in indonesia.

The process takes low-grade limonite type laterite-nickel ore as a raw material (the nickel content is generally about-1 percent, the total iron content is more than 40 percent), and takes sulfuric acid as a leaching agent to fully dissolve nickel, cobalt, iron and the like in the laterite-nickel ore under the leaching conditions of high temperature (250 ℃ below zero) and high pressure (5 MPa), and the leaching rate of the nickel and the cobalt reaches more than 90 percent. The dissolved iron ions are further hydrolyzed under high temperature and high pressure conditions to be transformed into hematite precipitate. The concentration of iron ions in the leachate is generally about 1-5 g/L, so in the existing production, sodium hydroxide or calcium hydroxide is usually added into the leachate to neutralize and remove impurity ions such as iron, and a vulcanizing agent or an alkaline substance is added into the leachate after the impurities are removed to precipitate nickel and cobalt into nickel-cobalt sulfide or hydroxide. In the high-pressure leaching process, the precipitated iron product cannot be effectively separated and utilized due to the fine particle size. According to statistics, more than 120 tons of acid iron-containing tailings are generated when 1 ton of nickel (calculated by metal) is extracted by high-pressure acid leaching, and the acid iron-containing tailings are generally discharged in deep sea by the conventional high-pressure acid leaching production line, so that the serious hidden danger of environmental pollution is brought.

Besides the low-grade limonite type lateritic nickel ore, the sapropel type lateritic nickel ore can efficiently dissolve valuable metals such as nickel, cobalt and the like through normal-pressure acid leaching because the nickel content is high and the main mineral is serpentine with good acid solubility, thereby avoiding the requirements of high-pressure acid leaching process on special equipment and the like. However, because the leaching rate of iron is high and different from high-pressure acid leaching, iron ions leached under the condition of normal-pressure leaching cannot be hydrolyzed, so that the concentration of the iron ions in the acid leaching solution is generally over 30g/L and is far higher than that of the leaching solution after high-pressure acid leaching. In addition, it is reported that the concentration of iron ions in acid leaching liquid is higher because of high iron content and high acid solubility in the ferronickel, when the nickel and cobalt are extracted from the crude ferronickel alloy produced by the prior ferronickel enterprises through acid dissolution. If the total iron content in the ferronickel crude alloy is 80% and can be totally dissolved by the acid, even in the liquid-solid ratio of 5:1, the iron ion concentration in the leachate of the leaching solution can also reach 160g/L. The existing research shows that in the process of removing iron by adopting the existing neutralization method, part of nickel and cobalt ions are adsorbed on ferric hydroxide precipitate and lost. When Fe is contained in the laterite-nickel ore leaching solution ³⁺ The concentration is 1.9g/L, and the loss rate of Ni and Co in the process of neutralizing and deironing is about 2 percent; but Fe ³⁺ When the concentration reaches 30g/L, the loss rate of nickel exceeds 12 percent. Obviously, when the concentration of iron ions in the leachate is too high, the iron ions removed by a neutralization method by adding an alkaline agent cannot be effectively separated and recovered.

Disclosure of Invention

Aiming at the problem of unsatisfactory iron and nickel cobalt separation selectivity in the separation process of valuable metals in a nickel cobalt leaching solution with high iron ion concentration, the invention provides a method for separating iron and nickel cobalt from a nickel cobalt leaching solution containing high-concentration iron ions, and aims to improve the separation selectivity of iron and nickel cobalt in a solution with high iron content, improve the recovery rate of elements and improve the purity of a product.

A method for separating iron and nickel and cobalt from nickel and cobalt acid leachate containing high-concentration iron ions comprises the steps of adding a phosphate source and a phosphorus-containing auxiliary agent into a solution to be treated containing iron ions, nickel ions and cobalt ions, reacting at the temperature of 10-50 ℃ and the pH value of 1.4-1.9 (also called as a first reaction), and then carrying out solid-liquid separation to obtain an iron phosphate product and a reaction liquid enriched with nickel and cobalt;

in the solution to be treated, the concentration of iron ions is more than or equal to 30g/L;

The phosphate source is at least one of phosphoric acid, alkali metal phosphate, alkali metal hydrogen phosphate, alkali metal dihydrogen phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate;

the phosphorus-containing adjuvant is at least one of sodium tripolyphosphate, sodium hexametaphosphate, potassium tripolyphosphate, potassium hexametaphosphate, ammonium tripolyphosphate and ammonium hexametaphosphate.

The research of the invention finds that the high iron concentration can obviously influence the separation selectivity and the separation efficiency of iron and nickel cobalt in the solution. In order to solve the problem, the research of the invention finds that under the combined control of the phosphate source, the phosphorus-containing auxiliary agent and the components, the combined control of the reaction temperature and the pH is further matched, so that the synergy can be realized, the problems of non-ideal separation selectivity and separation efficiency of iron and nickel cobalt caused by high iron concentration can be effectively solved, the iron recovery rate of single-stage reaction can be obviously improved, the loss of nickel and cobalt can be reduced, the separation selectivity of iron and nickel and cobalt can be obviously improved, and the reaction efficiency can be improved.

In the invention, the nickel-cobalt leaching solution comprises but is not limited to primary or secondary nickel-cobalt resources such as nickel ore, ferronickel and the like, which are obtained after acid leaching. Examples of the anion include chloride, sulfate, nitrate, and the like.

In the invention, the solution to be treated is allowed to contain ferrous ions, when the system contains ferrous ions, an oxidant is added in advance to oxidize the ferrous ions into ferric ions before the reaction, and the oxidant includes but is not limited to hydrogen peroxide, oxygen and the like.

The technical scheme of the invention is particularly suitable for the nickel-cobalt solution with high iron content, but does not exclude the situation that good iron-nickel-cobalt separation effect can be obtained in the solution system of the nickel-cobalt solution with low iron concentration.

In the invention, the concentration of the iron element in the solution to be treated is 30g/L to the concentration of a saturated solution, and preferably 30 to 100g/L.

In the solution to be treated of the present invention, the ion concentration of nickel and cobalt is not particularly required, for example, 0.1 to 10g/mL.

In the present invention, the molar ratio of P in the phosphate source to Fe in the solution to be treated (referred to as P/Fe molar ratio for short) can be adjusted according to the preparation requirement, for example, the molar ratio of P in the phosphate source to Fe in the solution to be treated is greater than or equal to 0.95, but considering the material cost and the material utilization rate, it is more preferably 0.95 to 1.05; more preferably 1 to 1.02.

In the invention, the combined control of the phosphate source and the phosphorus-containing auxiliary agent as well as the reaction temperature and the pH value is the key for synergistically improving the separation selection and the separation efficiency of iron and nickel cobalt in high-iron concentration.

In the invention, the phosphate source is at least one of phosphoric acid, alkali metal phosphate, alkali metal hydrogen phosphate, alkali metal dihydrogen phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate. The alkali metal element is, for example, sodium and/or potassium.

In the invention, the phosphorus-containing adjuvant is at least one of sodium tripolyphosphate, sodium hexametaphosphate, potassium tripolyphosphate, potassium hexametaphosphate, ammonium tripolyphosphate and ammonium hexametaphosphate.

In the invention, the proportion of the phosphate source and the phosphorus-containing auxiliary agent is controlled, which is beneficial to further synergistically improving the separation selectivity and separation efficiency of iron and nickel cobalt with high iron concentration.

Preferably, the mass ratio of the phosphate source to the phosphorus adjuvant is 1; preferably 1. Research shows that under the process, under the condition of an optimal proportion, better iron and nickel cobalt separation selectivity under high iron can be obtained unexpectedly, the purity of iron phosphate is improved, and lower nickel cobalt loss can be considered.

In the invention, the pH value of the system is controlled, which is beneficial to improving the separation selectivity and the separation efficiency of iron and nickel cobalt with high iron concentration. In the present invention, the pH refers to the pH at the beginning, during and at the end of the reaction. Preferably, the pH of the reaction is 1.5 to 1.9, preferably 1.6 to 1.9, and more preferably 1.7 to 1.8; the research of the invention finds that the process is further matched with the control of pH, so that the cooperation can be realized unexpectedly, the separation efficiency can be improved, the recovery rate of iron ions and the purity of iron phosphate can be improved, and the loss of nickel and cobalt can be reduced under the condition of ensuring good separation selectivity.

Preferably, the reaction temperature is 20 to 50 ℃, more preferably 25 to 35 ℃.

In the present invention, the reaction is carried out under stirring at the above-mentioned pH and temperature, and the time for the stirring reaction may be adjusted as necessary, and the reaction time is, for example, 30 to 60min in consideration of the treatment efficiency.

According to the preferable scheme of the invention, the pH value of the reaction liquid enriched with nickel and cobalt is further controlled to be 2.0-3.0, a second reaction is carried out, and second-stage iron phosphate and second-stage nickel and cobalt purified liquid are obtained through separation.

In the invention, the solution obtained by the first-stage reaction is further subjected to second-stage treatment, and the iron phosphate in the solution can be further precipitated by controlling the pH value, so that the nickel cobalt solution is further purified.

In the invention, two-stage ferric phosphate is added into a weak alkaline solution for transformation treatment, and after solid-liquid separation, the obtained filtrate is recycled (such as being recycled to a first reaction system) after being supplemented with phosphate sources and phosphorus-containing auxiliary agents in corresponding proportions; the obtained filter residue is an iron hydroxide product.

According to another preferable scheme of the invention, when the solution to be treated also contains at least one ion of aluminum, manganese and chromium, the pH of the nickel-cobalt second-stage purification solution is further controlled to be 4.5-6.0, a third reaction is carried out, and the third-stage slag and the nickel-cobalt third-stage purification solution are obtained through separation.

According to the invention, the pH value of the nickel cobalt second-stage purification solution or the nickel cobalt third-stage purification solution is controlled to be 8.0-9.0 according to the requirement, and precipitation reaction is carried out to prepare nickel cobalt hydroxide precipitate.

In the present invention, the base used for adjusting the pH is, for example, alkali metal hydroxide, ammonia water, etc.; the acid used is hydrochloric acid, sulfuric acid, etc.

The invention discloses a preferable treatment process, which comprises the following steps:

a) Adding phosphate source and phosphorus-containing auxiliary agent into the nickel cobalt acid leaching solution according to the iron/phosphorus molar ratio of 0.95-1.05, continuously stirring for 30-60 min at the temperature of 10-50 ℃ and the pH value of 1.4-1.9, and performing solid-liquid separation to obtain a first-stage filtrate and a first-stage iron phosphate product.

b) Continuously stirring the first-stage filtrate obtained in the step a) for 30-60 min at the pH value of 2.0-3.0, and then carrying out solid-liquid separation to obtain a second-stage filtrate and second-stage iron phosphate.

c) Continuously stirring the second-stage filtrate obtained in the step b) at the pH value of 8.0-9.0 for 20-60 min, and carrying out solid-liquid separation to obtain a nickel cobalt hydroxide product.

When impurity ions such as aluminum, manganese, chromium and the like exist in the nickel-cobalt leaching solution, the pH value of the second-stage filtrate is adjusted to 4.5-6.0 to remove the impurity ions, and then the step c is executed.

d) Adding the two-stage iron phosphate obtained in the step b) into a weak alkaline solution for dissolving, and after solid-liquid separation, circularly using the obtained filtrate in the step a after supplementing a phosphorus source in a corresponding proportion; the obtained filter residue is an iron hydroxide product and can be used as an iron-making raw material.

In the invention, the section of ferric phosphate obtained in the step a can be washed for 2-3 times by adopting weak acid solution with the same pH value as the precipitation, and then washed for 2-3 times by using industrial pure water to obtain a ferric phosphate product.

The obtained iron phosphate product of the first section has uniform granularity, the particle size is 400-600 nanometers, the purity is over 99.9 percent, the molar ratio of iron to phosphorus is 0.98-1.02, and the iron phosphate product can be used as a precursor of a lithium iron phosphate battery.

In the invention, after the first-stage precipitation in the step a, phosphate radicals and various metal ions are remained in the leaching solution, and preferably, the pH of the first-stage filtrate is continuously regulated to 2.0-3.0 to obtain second-stage iron phosphate containing other phosphates. Other phosphates are determined by impurity metal ions in the raw leachate, and are generally aluminum phosphate, chromium phosphate and the like.

B, adding the obtained two-stage ferric phosphate into a weakly alkaline solution for dissolving, enabling phosphate radicals to enter the solution again, converting iron into ferric hydroxide, and after solid-liquid separation, circularly using the obtained filtrate for the step a after supplementing a phosphorus source in a corresponding proportion; the obtained filter residue is an iron hydroxide product and can be used as an iron-making raw material.

The existing industrial wet process for treating the laterite-nickel ore is mainly a high-pressure acid leaching method, dissolved iron ions are hydrolyzed and precipitated again under the conditions of high temperature and high pressure, so that nickel and cobalt are selectively leached, and the concentration of the iron ions in the leaching solution is low and is generally less than 5g/L. The pH of the leachate is adjusted by adding sodium hydroxide or calcium hydroxide, a micelle structure of ferric hydroxide is formed when neutralizing and precipitating ferric ions, and nickel ions, cobalt ions and the like are simultaneously precipitated as counter ions of an adsorption layer, so that the loss of nickel and cobalt in the process of neutralizing and removing iron is caused. Because the iron ion concentration in the leachate obtained by the high-pressure acid leaching method is low, the loss of nickel and cobalt is less. However, when the normal-pressure leachate or the ferronickel smelted by a pyrogenic process is used as a raw material for leaching, the concentration of iron ions in the leachate is far higher than that of the high-pressure leachate, so that the yield of iron hydroxide is high in the precipitation process, particles are mutually aggregated, the loss of nickel and cobalt is remarkably improved, the iron and the nickel and cobalt cannot be effectively separated, and the feasibility of the process is greatly reduced; and the precipitated iron is difficult to be reused and is mainly used for stockpiling treatment of tailings.

In the process of precipitation, iron ions are precipitated in the form of iron phosphate, and the method is also a method for effectively separating iron from nickel and cobalt from a solution. However, during the precipitation process, the formation of a large amount of iron phosphate and the growth of particles thereof can significantly increase the concomitant precipitation of nickel and cobalt, thereby resulting in the loss of nickel and cobalt. Therefore, under the synergistic combination of the phosphate source and the phosphorus-containing auxiliary agent and the combined control of reaction temperature and pH, the side reaction can be controlled, the nucleation reaction selectivity of the iron phosphate can be effectively improved, the nucleation morphology can be improved, the iron precipitation efficiency can be improved, the selective precipitation of iron can be controlled, and the separation selectivity and separation efficiency of iron and nickel cobalt under high iron concentration can be improved.

In the invention, the ferric phosphate obtained by the reaction reaches the battery grade, and under the optimized process of the invention, the single-pass recovery rate is high, and in addition, the method of the invention has low loss of nickel and cobalt, for example, the recovery rate of nickel and cobalt in the whole process is more than 95%. Moreover, the method has the advantages of low cost in the treatment process, simple process, cyclic utilization of the medicament, low three-waste output and environmental protection.

Drawings

FIG. 1 is a graph showing the particle size analysis of a stage of the precipitated slag in example 1.

FIG. 2 is a scanning electron micrograph of a section of the precipitated slag in example 2.

FIG. 3 is a graph showing the particle size analysis of a first stage of the precipitated slag in example 2.

FIG. 4 is a scanning electron microscope-energy spectrum analysis chart of the precipitation slag of comparative example 1;

FIG. 5 is a scanning electron microscope-energy spectrum analysis chart of the precipitation slag of comparative example 2;

as can be seen from fig. 1 to 3, in the production process of the present invention, the precipitate obtained by iron phosphate precipitation is uniform in shape and small in particle size. However, comparing fig. 4 and fig. 5, when iron is removed by conventional neutralization precipitation, and calcium hydroxide and sodium hydroxide are used as neutralizing agents for precipitation, the precipitation slag has large particle size, and the precipitation slag contains nickel and cobalt, which indicates that a large amount of nickel and cobalt is lost in the process of iron precipitation.

Detailed Description

The data of the examples are only for clearly illustrating the contents of the present invention, and the scope of application of the present invention is not limited by the scale of the experiments and the data in the above examples.

In the following cases, the concentrations of the main metal ions of the nickel cobalt leach liquor (sulfuric acid leach liquor) used are shown in table 1, unless otherwise stated. The solution is described by way of example only and is not intended to necessarily limit the technical scope of the present invention.

TABLE 1 Nickel cobalt leachate Main Metal ion concentration (g/L)

Example 1:

adding phosphoric acid (phosphate source) and a phosphorus-containing auxiliary agent (sodium tripolyphosphate) into the nickel cobalt acid leaching solution at the temperature of 30 ℃, wherein the molar ratio of phosphorus in the phosphate source to iron (P/Fe) in the nickel cobalt acid leaching solution is 1.02, the mass ratio of the phosphate source to the phosphorus-containing auxiliary agent is 1.29, stirring and reacting (first-stage reaction) for 35min at the pH of 1.6 and the temperature of 30 ℃, and then carrying out solid-liquid separation to obtain a first-stage residual solution and an iron phosphate (first-stage iron phosphate) product. The retention rate of iron ions in the first-stage residual liquid is 45.1 percent, and the retention rate is higher, which indicates that the iron ions are not completely precipitated, thereby increasing the difficulty for subsequently separating other ions, and the retention rates of nickel, cobalt, magnesium, aluminum and manganese are all 100 percent.

Adjusting the pH value of the first-stage residual liquid to 3.0, and performing solid-liquid separation to obtain a second-stage precipitation slag and a second-stage residual liquid, wherein the retention rates of nickel, cobalt and magnesium in the second-stage residual liquid are 100%, and the retention rates of iron, aluminum and manganese ions are 0.4%, 15.4% and 35.1%.

The pH value of the second-stage residual liquid is adjusted to 6.0, the nickel and magnesium retention rate in the third-stage residual liquid after solid-liquid separation is 100%, the cobalt retention rate is 82.3%, and the iron, aluminum and manganese ion retention rates are all lower than 0.1%.

And adjusting the pH value of the three-section residual liquid to 9.0, and performing solid-liquid separation to obtain the nickel hydroxide cobalt, wherein the nickel recovery rate is 98 percent and the cobalt recovery rate is 100 percent.

The second-stage leached residue reacts for 5min in 0.5M sodium hydroxide solution at 30 ℃, the phosphorus dissolution rate exceeds 95 percent, and the second-stage leached residue can be recycled after a phosphorus source is supplemented.

Example 2:

compared with example 1, the difference is only that the pH of one stage of reaction is regulated and controlled as follows:

group A experiment: the pH of the first stage reaction was controlled at 1.8.

The retention rate of iron ions in the obtained first-stage residual liquid is 7.1 percent, and the retention rates of nickel, cobalt, magnesium, aluminum and manganese are all 100 percent; the molar ratio of iron to phosphorus in the obtained iron phosphate (first-stage iron phosphate) product is 1.0, the impurity content is less than 0.01%, and the industrial standard (HG-T4701-2014) of the iron phosphate for the battery is met.

Group B experiments: the pH of the first stage reaction was controlled at 1.5.

The results were: the retention rate of iron ions in the first-stage residual liquid is 68.3 percent, and the retention rates of nickel, cobalt, magnesium, aluminum and manganese are all 100 percent; the yield of the obtained iron phosphate (one-stage iron phosphate) is low.

Group C experiments: the pH of the first stage reaction was controlled at 1.7.

The results were: the retention rate of iron ions in the first-stage residual liquid is 8.4%, the retention rates of nickel, cobalt, magnesium, aluminum and manganese are respectively 99.7%, 99.3%, 100% and 100%, the iron/phosphorus molar ratio in the obtained iron phosphate (first-stage iron phosphate) product is 1.0, the impurity content is less than 0.01%, and the industrial standard of iron phosphate for batteries (HG-T4701-2014) is met.

Group D experiments: the pH of the first stage reaction was controlled at 1.9.

The results were: the retention rate of iron ions in the first-stage residual liquid is 2.1 percent, and the retention rates of nickel, cobalt, magnesium, aluminum and manganese are 93.2 percent, 94.6 percent, 90.4 percent and 90.7 percent respectively; the impurity content of the obtained iron phosphate (first-stage iron phosphate) product is relatively increased, which shows that other ions such as nickel, cobalt and the like can be precipitated by an excessively high pH value, and the quality of the product is influenced.

Example 3:

the only difference compared to the group a case of example 2 was that sodium phosphate was used as the phosphate source and the other operations and parameters were the same as for group a of example 2. The determination shows that: the retention rate of iron ions in the first-stage residual liquid is 3.2 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 99.1 percent, 98.6 percent, 100 percent and 100 percent; the molar ratio of iron to phosphorus in the obtained iron phosphate product (a section of iron phosphate) is 1.0, the impurity content is less than 0.01 percent, and the iron phosphate product meets the industrial standard of iron phosphate for batteries (HG-T4701-2014).

Example 4:

compared with the group A case of the example 2, the difference is only that the dosage of the phosphorus-containing adjuvant is adjusted to ensure that the mass ratio of the phosphate source to the phosphorus-containing adjuvant is 1; the other conditions were the same as in group A of example 2.

The test finds that: the retention rate of iron ions in the first-stage residual liquid is 0.18 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are 97.32 percent, 95.4 percent, 98.2 percent and 97.4 percent respectively; the iron/phosphorus molar ratio in the obtained iron phosphate product (one-stage iron phosphate) is 0.94, and the purity of the product is reduced along with certain impurities.

Example 5

Compared with the group A case of the example 2, the difference is only that the dosage of the phosphorus-containing adjuvant is adjusted to ensure that the mass ratio of the phosphate source to the phosphorus-containing adjuvant is 1; the other conditions were the same as those in group A of example 2. Tests show that the retention rate of iron ions in the first-stage residual liquid is 6.18%, and the retention rates of nickel, cobalt, magnesium and manganese ions are 93.7%, 92.6%, 95.4% and 96.1% respectively; the iron/phosphorus molar ratio in the obtained iron phosphate product (one-stage iron phosphate) is 1.01, certain impurities exist, and the purity of the product is reduced.

Example 6

Compared with group A of example 2, the difference is that the reaction temperature of the first-stage reaction is 50 ℃, the phosphorus/iron molar ratio is 0.95; the phosphorus-containing adjuvant is sodium hexametaphosphate. The research shows that the retention rate of iron ions in the first-stage residual liquid is 5.6 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are 91.2 percent, 88.6 percent, 84.7 percent and 89.1 percent respectively; the iron/phosphorus molar ratio in the obtained iron phosphate product (one-stage iron phosphate) is 1.1, certain impurities exist, and the purity of the product is reduced.

Comparative example 1:

the only difference from example 1 is that the temperature of the first stage reaction is 80 ℃. The research shows that the retention rate of iron ions in the first-stage residual liquid is 40.8 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 62.5 percent, 56.7 percent, 61.8 percent and 76.5 percent; the molar ratio of iron to phosphorus in the obtained iron phosphate product (a section of iron phosphate) is 1.4, and the iron phosphate product contains a certain amount of ferric hydroxide and has high impurity content.

Comparative example 2:

the only difference from example 1 is that the phosphorus-containing adjuvant sodium tripolyphosphate was not added. After the first-stage reaction, carrying out solid-liquid separation to obtain a first-stage residual liquid and an iron phosphate product; the retention rate of iron ions in the first-stage residual liquid is 38.7 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 74.3 percent, 61.4 percent, 72.5 percent and 84.3 percent; the iron/phosphorus molar ratio of the obtained iron phosphate product (first-stage iron phosphate) is 1.0, and the impurity content is high.

Comparative example 3

Compared with the example 1, the difference is only that no phosphoric acid is added, but pure sodium tripolyphosphate is adopted (the molar amounts of Fe and P in the system are not changed); after the first-stage reaction, carrying out solid-liquid separation to obtain a first-stage residual liquid and an iron phosphate product (first-stage iron phosphate); the retention rate of iron ions in the first-stage residual liquid is 32.6 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 68.4 percent, 46.7 percent, 80.3 percent and 58.4 percent; the iron/phosphorus molar ratio in the obtained iron phosphate product is 0.03, which indicates that iron ions are precipitated in the form of ferric hydroxide micelles, and the micelles carry a large amount of nickel, cobalt, magnesium and manganese ions, so that the impurity content is high.

Comparative example 4

The only difference compared to example 1 is that the phosphorus-containing adjuvant of the present invention is replaced by another P material (pyrophosphate). After the first-stage reaction, carrying out solid-liquid separation to obtain a first-stage residual liquid and an iron phosphate product; the retention rate of iron ions in the first-stage residual liquid is 42.5 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 70.2 percent, 57.4 percent, 69.8 percent and 71.3 percent; the iron/phosphorus molar ratio of the obtained iron phosphate product (first-stage iron phosphate) is 1.0, and the impurity content is high.

Comparative example 5

The only difference compared to example 1 is that the pH of the first stage reaction was 2.0. After the first-stage reaction, carrying out solid-liquid separation to obtain a first-stage residual liquid and an iron phosphate product (first-stage iron phosphate); the retention rate of iron ions in the first-stage residual liquid is 1.2 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are respectively 87.3 percent, 90.6 percent, 86.4 percent and 84.9 percent; the molar ratio of iron to phosphorus in the obtained iron phosphate product is 1.4, which indicates that the generated product contains ferric hydroxide and carries nickel, cobalt, magnesium and manganese ions, so that the impurity content is high.

Comparative example 6

The only difference compared to example 1 is that the pH of the one-stage reaction was 1.2. The result is that solid-liquid separation is carried out after the first-stage reaction to obtain a first-stage residual liquid and an iron phosphate product (first-stage iron phosphate); the retention rate of iron ions in the first-stage residual liquid is 98.4 percent, and the retention rates of nickel, cobalt, magnesium and manganese ions are all 100 percent; almost no precipitation occurred, indicating that a pH of 1.2 did not precipitate the iron phosphate.

Comparative example 7:

when the temperature is 30 ℃, adding a calcium hydroxide solution into the nickel cobalt acid leaching solution to adjust the pH value to 3.0; solid-liquid separation, wherein the retention rates of iron, nickel, cobalt, magnesium, aluminum and manganese ions in the residual liquid are respectively 1.4%, 63.9%, 51.7%, 75.4%, 41.5% and 49.4%. The calcium hydroxide solution can precipitate most of iron ions, but cannot effectively separate the iron ions from valuable metal ions such as nickel, cobalt and the like in the acid leaching solution.

Comparative example 8:

compared with comparative example 7, the difference is only that the pH is adjusted to 3.0 by adding sodium hydroxide solution to the nickel cobalt acid; solid-liquid separation, wherein the retention rates of iron, nickel, cobalt, magnesium, aluminum and manganese ions in the residual liquid are 14.3%, 74.3%, 68.7%, 78.5%, 61.6% and 63.2% respectively. The sodium hydroxide solution can not effectively separate iron ions from valuable metal ions such as nickel, cobalt and the like in the leaching solution.

Claims (12)

1. A method for separating iron and nickel and cobalt from nickel and cobalt acid leachate containing high-concentration iron ions is characterized in that a phosphate source and a phosphorus-containing auxiliary agent are added into a solution to be treated containing iron ions, nickel ions and cobalt ions, the reaction is carried out at the temperature of 25 to 35 ℃ and the pH of 1.7 to 1.8, and then solid-liquid separation is carried out to obtain an iron phosphate product and a reaction liquid enriched with nickel and cobalt;

in the solution to be treated, the concentration of iron ions is more than or equal to 30g/L;

the phosphate source is at least one of phosphoric acid, alkali metal phosphate, alkali metal hydrogen phosphate, alkali metal dihydrogen phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate;

the phosphorus-containing adjuvant is at least one of sodium tripolyphosphate, sodium hexametaphosphate, potassium tripolyphosphate, potassium hexametaphosphate, ammonium tripolyphosphate and ammonium hexametaphosphate;

The molar ratio of P in the phosphate source to Fe in the solution to be treated is 0.95 to 1.05;

the mass ratio of the phosphate source to the phosphorus adjuvant is 1 to 0.1-0.5.

2. The method as claimed in claim 1, wherein the solution to be treated is allowed to contain ferrous ions, and the solution to be treated is subjected to oxidation treatment in advance before the reaction.

3. The method of claim 2, wherein the oxidizing agent for the oxidation treatment is at least one of hydrogen peroxide and oxygen.

4. The method according to claim 1, wherein the concentration of elemental iron in the solution to be treated is between 30g/L and the concentration of a saturated solution.

5. The method according to claim 4, wherein the concentration of the iron element in the solution to be treated is 30 to 100g/L.

6. The method of claim 1, wherein the molar ratio of P in the phosphate source to Fe in the solution to be treated is from 1 to 1.02.

7. The method according to claim 1, wherein the mass ratio of the phosphate source to the phosphorus adjuvant is 1.

8. The process according to claim 1, wherein the reaction time is 30 to 60min.

9. The method according to any one of claims 1 to 8, wherein the pH of the reaction liquid rich in nickel and cobalt is controlled to be 2.0 to 3.0, and the second reaction is carried out to separate and obtain second-stage iron phosphate and second-stage nickel and cobalt purified liquid.

10. The method as claimed in claim 9, wherein the second-stage ferric phosphate is added into weak alkaline solution for transformation treatment, and after solid-liquid separation, the obtained filtrate is recycled after supplementing phosphate source and phosphorus-containing adjuvant in corresponding proportion; the obtained filter residue is an iron hydroxide product.

11. The method of claim 9, wherein when the solution to be treated further contains at least one ion of aluminum, manganese and chromium, the pH of the nickel cobalt secondary purification solution is further controlled to be 4.5 to 6.0, a third reaction is carried out, and the third-stage slag and the nickel cobalt tertiary purification solution are separated.

12. The method of claim 11, wherein the pH of the nickel cobalt three-stage purification solution is controlled to be 8.0 to 9.0, and precipitation reaction is carried out to obtain nickel cobalt hydroxide precipitate.

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