A two-stage normal pressure hydrochloric acid combined leaching method for laterite nickel ore

Abstract

A two-stage atmospheric pressure hydrochloric acid combined leaching method for lateritic nickel ore relates to the field of wet processing technology for lateritic nickel ore. The method first involves leaching limonite-type lateritic nickel ore powder with hydrochloric acid at atmospheric pressure, yielding a primary leaching solution and a primary leaching residue. The primary leaching solution is then mixed with siliceous-magnesian-type lateritic nickel ore for a secondary leaching, yielding a secondary leaching solution and a secondary leaching residue. The secondary leaching residue is returned to be mixed with limonite-type lateritic nickel ore for a primary acid leaching. The secondary leaching solution is neutralized to precipitate iron and aluminum, and nickel, yielding iron-aluminum slag, nickel-cobalt slag, and magnesium chloride solution. The nickel-cobalt slag is refined to obtain nickel-cobalt products. The magnesium chloride waste liquid is pyrolyzed to obtain hydrochloric acid and magnesium oxide. This method can improve the comprehensive utilization rate of hydrochloric acid, reduce the solution treatment volume and the amount of hydrochloric acid and magnesium oxide added, increase the nickel ion concentration in the solution, and improve the filtration performance of the leaching solution, thus possessing significant socio-economic value.

Description

Technical Field

[0001] This invention belongs to the field of wet processing technology for laterite nickel ore. Specifically, this invention relates to a two-stage atmospheric pressure hydrochloric acid leaching method for laterite nickel ore. Background Technology

[0002] With the depletion of sulfide nickel ore resources, the development and utilization of laterite nickel ore, which accounts for more than 70% of the world's nickel resources, is receiving increasing attention. Laterite nickel ore is mainly divided into two categories: limonite and magnesia. Limonite is generally located in the upper layer of the deposit, characterized by high iron, low nickel, low silicon and magnesium content, and high cobalt content. Magnesia is generally located in the lower layer of the deposit, characterized by high silicon and magnesium content, high nickel content, and relatively low iron and cobalt content. Existing laterite nickel ore smelting processes mainly include pyrometallurgical nickel-iron smelting and hydrometallurgical high-pressure sulfuric acid leaching. Pyrometallurgical smelting processes involve high reaction temperatures and cannot directly produce nickel sulfate required by the new energy industry. Hydrometallurgical high-pressure sulfuric acid leaching processes have harsh production conditions, generate large amounts of sulfur-containing waste residue that cannot be directly utilized, and can only be used to process limonite-type laterite nickel ore. Hydrochloric acid leaching has advantages such as mild reaction conditions and easy utilization of slag. However, since the hydrochloric acid leaching process is a normal pressure reaction and there is no high-temperature hydrolysis of iron, the acid consumption is relatively high, the concentration of nickel-cobalt leaching solution is low, and the concentration is low when leaching limonite-type laterite nickel ore. In addition, most of the iron and magnesium are leached out during the leaching process, resulting in a low concentration of nickel-cobalt in the later stages. More neutralizing agents need to be added, the equipment occupies a large area, and the treatment of impurities is relatively complicated.

[0003] Chinese patent CN201310081590.0 uses hydrochloric acid leaching followed by high-temperature direct calcination to process lateritic nickel ore. This process results in low nickel-cobalt concentrations, high residual acid concentrations in the leachate, and difficulties in subsequent refining, leading to high costs. Chinese patent CN202010991516.2 uses hydrochloric acid pressure leaching of lateritic nickel ore. This method involves high reaction temperatures, low nickel-cobalt concentrations, and complex separation of iron and silicon slag, impacting the process's economic viability. Chinese patent CN201910018300.5 uses a mixed leaching method with limonite and serpentine-type lateritic nickel ore. While this increases the nickel-cobalt concentration in the leachate, it is due to the use of high-nickel serpentine-type ore. Furthermore, the residual acid in the leachate remains unutilized, requiring significant neutralization and resulting in high economic costs. Chinese patent CN201910018386.1 uses room temperature acid leaching of laterite nickel ore, which also has problems such as the ineffective utilization of residual acid and the large amount of neutralizing agent added and the long neutralization reaction time.

[0004] In summary, given the problems of large residual acid volume, difficulty in filtering and separating leaching slurry from limonite-type laterite nickel ore, and low concentration of nickel and cobalt elements in existing hydrochloric acid leaching processes, there is an urgent need to develop a laterite nickel ore processing technology that can improve acid utilization, obtain high-concentration nickel and cobalt leachate, and require less equipment investment. Summary of the Invention

[0005] In view of the defects and deficiencies in the prior art, the present invention provides a two-stage atmospheric pressure hydrochloric acid leaching method for laterite nickel ore, in order to at least partially solve at least one of the aforementioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A two-stage atmospheric pressure hydrochloric acid leaching method for laterite nickel ore, comprising the following steps:

[0008] 1) The ground limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid are mixed and reacted in a reactor under normal pressure. The reaction conditions are: hydrochloric acid concentration ≥30%, leaching temperature 80-120℃, and leaching time 1-3h. After the reaction, liquid-solid separation is performed to obtain primary leaching solution and primary leaching residue. The primary leaching residue is washed with water to obtain silica slag, which is used to prepare building materials.

[0009] 2) The ground ferrosilicon-magnesium type laterite nickel ore is mixed with the primary leaching solution and reacted in a reactor under normal pressure. The reaction conditions are: temperature 80-120℃, leaching time 1-3h. After the reaction, the liquid and solid are separated to obtain secondary leaching solution and secondary leaching residue. The secondary leaching residue is returned to the primary leaching.

[0010] 3) Add magnesium oxide to the secondary leachate in sequence to neutralize and precipitate iron, aluminum, nickel and cobalt in steps, to obtain iron-aluminum slag, nickel-cobalt slag and magnesium chloride solution. The magnesium chloride solution is then used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0011] Preferably, the iron content in the limonite-type lateritic nickel ore powder in step 1) is ≥30%; and the iron content in the siliceous-magnesium-type lateritic nickel ore powder in step 2) is ≤20%.

[0012] The mass of the ferrosilicon-magnesium type lateritic nickel ore powder mentioned in step 2) is 20-60% of the mass of the limonite type lateritic nickel ore powder mentioned in step 1).

[0013] This invention can improve the comprehensive utilization rate of hydrochloric acid, reduce the amount of solution to be processed and the amount of hydrochloric acid and magnesium oxide added, increase the concentration of nickel ions in the solution, and improve the filtration performance of the leachate, thus having great social and economic value.

[0014] This invention addresses the problems encountered in existing hydrochloric acid atmospheric pressure leaching processes by proposing a novel method for treating laterite nickel ore, involving a two-step atmospheric pressure reaction and the return of the secondary leaching residue to the primary leaching process. This method offers the following main advantages:

[0015] 1) This invention mixes the primary leaching solution with ferrosilicon-magnesium type laterite nickel ore for atmospheric pressure leaching, which improves the utilization rate of hydrochloric acid and the concentration of nickel, cobalt, iron and magnesium in the leaching solution, reduces the acidity of the leaching solution, reduces the amount of subsequent neutralizing agent used, and improves equipment utilization.

[0016] 2) This invention returns the secondary leaching residue to the first leaching, further improving the leaching rate of high-nickel silicomagnesia type laterite nickel ore. At the same time, the addition of the secondary leaching residue enhances the liquid-solid separation performance of the first leaching slurry.

[0017] 3) This invention enables stepwise leaching of limonite-type and siliceous-magnesium-type lateritic nickel ore under normal pressure, expanding the application range of hydrochloric acid processing of lateritic nickel ore raw materials and providing a new path for hydrometallurgical smelting of lateritic nickel ore. Attached Figure Description

[0018] Figure 1 This is a flowchart of the two-stage atmospheric pressure hydrochloric acid combined leaching method for laterite nickel ore according to the present invention. Detailed Implementation

[0019] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0020] Lateritic nickel ore of limonite and lateritic nickel ore of silicon magnesium were crushed and ball-milled separately, and the resulting ore powder was used as raw material. The milled limonite lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. After the reaction, liquid-solid separation was performed to obtain primary leaching solution and primary leaching residue. Milled lateritic nickel ore of silicon magnesium (20-60% by weight) was mixed with the primary leaching solution and reacted in a reactor under normal pressure. After the reaction, liquid-solid separation was performed to obtain secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching process. The secondary leaching solution was neutralized to precipitate iron, aluminum, and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0021] Example 1

[0022] Limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 31%, leaching temperature 120℃, and leaching time 1 hour. After the reaction, liquid-solid separation yielded a primary leaching solution, which was mixed with 40% siliceous-magnesian lateritic nickel ore in a reactor under normal pressure. The reaction conditions were: temperature 80℃, and leaching time 1 hour. After the reaction, liquid-solid separation yielded a secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching. The secondary leaching solution was added stepwise to magnesium oxide to neutralize and precipitate iron-aluminum and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare the corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0023] The leaching rates of nickel and cobalt in the first leaching reaction were 99.2% and 99.5%, respectively, with nickel and cobalt concentrations in the leachate of 4.62 g / L and 0.42 g / L, respectively. In the second leaching reaction, the leaching rates of nickel and cobalt were 88.0% and 92.5%, respectively, with nickel and cobalt concentrations in the leachate of 5.89 g / L and 0.51 g / L, respectively. The filtration time of the slurry in the first leaching reaction was 64% of that in Comparative Example 1, and the pH of the second leaching solution was 0.35.

[0024] Comparative Example 1

[0025] The ground limonite-type lateritic nickel ore powder was mixed with a certain amount of hydrochloric acid and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 31%, leaching temperature 120℃, and leaching time 1 hour. After the reaction, liquid-solid separation was performed to obtain leachate and leaching residue. The leaching rates of nickel and cobalt in the hydrochloric acid leaching reaction were 99.3% and 99.4%, respectively, and the concentrations of nickel and cobalt in the leachate were 3.53 g / L and 0.30 g / L, respectively. The pH of the leachate was -1.53, and the filtration time was 25 minutes.

[0026] Example 2

[0027] Limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 30%, leaching temperature 80℃, and leaching time 3 hours. After the reaction, liquid-solid separation yielded a primary leaching solution, which was mixed with 20% siliceous-magnesian lateritic nickel ore in a reactor under normal pressure. The reaction conditions were: temperature 80℃, leaching time 2 hours. After the reaction, liquid-solid separation yielded a secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching. The secondary leaching solution was added stepwise to magnesium oxide to neutralize and precipitate iron-aluminum and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare the corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0028] The leaching rates of nickel and cobalt in the first leaching reaction were 95.1% and 94.8%, respectively, with nickel and cobalt concentrations in the leachate of 3.60 g / L and 0.34 g / L, respectively. In the second leaching reaction, the leaching rates of nickel and cobalt were 85.8% and 88.1%, respectively, with nickel and cobalt concentrations in the leachate of 4.44 g / L and 0.40 g / L, respectively. The filtration time of the slurry in the first leaching reaction was 76% of that in Comparative Example 2, and the pH of the second leaching solution was 0.15.

[0029] Comparative Example 2

[0030] The ground limonite-type lateritic nickel ore powder was mixed with a certain amount of hydrochloric acid and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 30%, leaching temperature 80℃, and leaching time 3 hours. After the reaction, liquid-solid separation was performed to obtain leachate and leaching residue. The leaching rates of nickel and cobalt in the hydrochloric acid leaching reaction were 95.4% and 95.2%, respectively, and the concentrations of nickel and cobalt in the leachate were 3.41 g / L and 0.29 g / L, respectively. The pH of the leachate was -1.75, and the filtration time was 22 minutes.

[0031] Example 3

[0032] Limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 31%, leaching temperature 105℃, and leaching time 1.5h. After the reaction, liquid-solid separation yielded a primary leaching solution, which was mixed with 60% siliceous-magnesian lateritic nickel ore in a reactor under normal pressure. The reaction conditions were: temperature 105℃, leaching time 1.5h. After the reaction, liquid-solid separation yielded a secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching. The secondary leaching solution was added stepwise to magnesium oxide to neutralize and precipitate iron-aluminum and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare the corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0033] The leaching rates of nickel and cobalt in the first leaching reaction were 98.9% and 99.0%, respectively, with nickel and cobalt concentrations in the leachate of 5.50 g / L and 0.49 g / L, respectively. In the second leaching reaction, the leaching rates of nickel and cobalt were 85.2% and 84.4%, respectively, with nickel and cobalt concentrations of 6.68 g / L and 0.58 g / L, respectively. The filtration time of the slurry in the first leaching reaction was 45% of that in Comparative Example 3, and the pH of the second leaching solution was 0.21.

[0034] Comparative Example 3

[0035] The ground limonite-type lateritic nickel ore powder was mixed with a certain amount of hydrochloric acid and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 31%, leaching temperature 105℃, and leaching time 1.5 h. After the reaction, liquid-solid separation was performed to obtain leachate and leaching residue. The leaching rates of nickel and cobalt in the hydrochloric acid leaching reaction were 99.0% and 99.1%, respectively, and the concentrations of nickel and cobalt in the leachate were 3.47 g / L and 0.30 g / L, respectively. The pH of the leachate was -1.43, and the filtration time was 28 minutes.

[0036] Example 4

[0037] Limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 35%, leaching temperature 110℃, and leaching time 1 hour. After the reaction, liquid-solid separation yielded a primary leaching solution, which was mixed with 30% siliceous-magnesian lateritic nickel ore in a reactor under normal pressure. The reaction conditions were: temperature 120℃, and leaching time 1 hour. After the reaction, liquid-solid separation yielded a secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching. The secondary leaching solution was added stepwise to magnesium oxide to neutralize and precipitate iron-aluminum and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare the corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0038] The leaching rates of nickel and cobalt in the first leaching reaction were 99.1% and 99.1%, respectively, with nickel and cobalt concentrations in the leachate of 5.66 g / L and 0.50 g / L, respectively. In the second leaching reaction, the leaching rates of nickel and cobalt were 88.7% and 87.6%, respectively, with nickel and cobalt concentrations in the leachate of 7.07 g / L and 0.60 g / L, respectively. The filtration time of the slurry in the first leaching reaction was 67% of that in Comparative Example 4, and the pH of the second leaching solution was 0.30.

[0039] Comparative Example 4

[0040] The ground limonite-type lateritic nickel ore powder was mixed with a certain amount of hydrochloric acid and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 35%, leaching temperature 110℃, and leaching time 1 hour. After the reaction, liquid-solid separation was performed to obtain leachate and leaching residue. The leaching rates of nickel and cobalt in the hydrochloric acid leaching reaction were 99.2% and 99.0%, respectively, and the concentrations of nickel and cobalt in the leachate were 4.70 g / L and 0.41 g / L, respectively. The pH of the leachate was -1.66.

[0041] Example 5

[0042] Limonite-type lateritic nickel ore powder, secondary leaching residue, and a certain amount of hydrochloric acid were mixed and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 32%, leaching temperature 100℃, and leaching time 2 hours. After the reaction, liquid-solid separation yielded a primary leaching solution, which was mixed with 50% siliceous-magnesian lateritic nickel ore in a reactor under normal pressure. The reaction conditions were: temperature 80℃, and leaching time 1 hour. After the reaction, liquid-solid separation yielded a secondary leaching solution and secondary leaching residue. The secondary leaching residue was returned to the primary leaching. The secondary leaching solution was added stepwise to magnesium oxide to neutralize and precipitate iron-aluminum and nickel-cobalt, yielding iron-aluminum slag and nickel-cobalt slag, which were used to prepare the corresponding products. Magnesium chloride solution was used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

[0043] The leaching rates of nickel and cobalt in the first leaching reaction were 98.7% and 99.1%, respectively, with nickel and cobalt concentrations in the leachate of 4.62 g / L and 0.42 g / L, respectively. In the second leaching reaction, the leaching rates of nickel and cobalt were 82.5% and 84.1%, respectively, with nickel and cobalt concentrations in the leachate of 5.39 g / L and 0.48 g / L, respectively. The filtration time of the slurry in the first leaching reaction was 53% of that in Comparative Example 5, and the pH of the second leaching solution was 0.19.

[0044] Comparative Example 5

[0045] The ground limonite-type lateritic nickel ore powder was mixed with a certain amount of hydrochloric acid and reacted in a reactor under normal pressure. The reaction conditions were: hydrochloric acid concentration 32%, leaching temperature 100℃, and leaching time 2 hours. After the reaction, liquid-solid separation was performed to obtain leachate and leaching residue. The leaching rates of nickel and cobalt in the hydrochloric acid leaching reaction were 98.9% and 99.1%, respectively, and the concentrations of nickel and cobalt in the leachate were 4.65 g / L and 0.41 g / L, respectively. The pH of the leachate was -1.64.

[0046] The upper and lower limits of the process parameters (such as temperature, time, etc.) and the range values ​​of the present invention can all achieve the method, and examples are not listed here.

[0047] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A two-stage atmospheric pressure hydrochloric acid leaching method for laterite nickel ore, the method comprising the following steps: 1) The ground limonite-type laterite nickel ore powder, secondary leaching residue and a certain amount of hydrochloric acid are mixed and subjected to an acid leaching reaction at normal pressure in a reactor. After the reaction, the liquid and solid are separated to obtain primary leaching solution and primary leaching residue. The primary leaching residue is washed with water to obtain silica slag, which is used to prepare building materials. The hydrochloric acid concentration is ≥30%, the leaching temperature is 80-120℃ and the leaching time is 1-3h. 2) The ground ferrosilicon-magnesium lateritic nickel ore is mixed with the primary leaching solution and subjected to an acid leaching reaction at atmospheric pressure in a reactor. After the reaction, liquid-solid separation is performed to obtain a secondary leaching solution and a secondary leaching residue. The secondary leaching residue is returned to the primary acid leaching. The reaction temperature for the secondary acid leaching is 80-120℃, and the leaching time is 1-3 hours. The mass of the ferrosilicon-magnesium lateritic nickel ore powder is 20-60% of the mass of the limonite-type lateritic nickel ore powder in step 1). 3) Add magnesium oxide to the secondary leachate to neutralize and precipitate iron, aluminum, nickel and cobalt in steps to obtain iron-aluminum slag, nickel-cobalt slag and magnesium chloride solution. The magnesium chloride solution is then used for pyrolysis to regenerate magnesium oxide and hydrochloric acid.

2. The method according to claim 1, wherein the method is characterized by, In step 1), the iron content in the goethite-type laterite nickel ore powder is ≥30%.

3. The method according to claim 1, wherein the method is characterized by, In step 2), the iron content in the silica-magnesium type laterite nickel ore powder is ≤20%.

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