Method for synergic leaching of laterite nickel ore and nickel matte alloy

Abstract

The present application relates to the field of chemical metallurgy, and particularly relates to a method for synergic leaching of laterite nickel ore and nickel matte alloy; the technical scheme comprises washing and selecting, and synergic leaching, and the synergic leaching step is specifically divided into two-stage leaching, wherein the first-stage leaching is diluting the washed and selected low-magnesium high-iron high-nickel transition type ore slurry to 15%-25% concentration, then adding 98% concentration sulfuric acid according to the acid-ore mass ratio of (1.5-2.5):1, and stirring and leaching at constant temperature 85℃ for 4-6h, and the second-stage leaching is mixing the filtrate obtained in the first-stage leaching with limonite slurry, and adding into an autoclave for oxygen pressure reaction; the present application has wide application range of raw materials, high leaching rate, and is more environmentally friendly, the nickel production capacity of the autoclave of the same volume is doubled, the low-value nickel in the nickel-iron concentrate powder is converted into high-value nickel in a short process and at low cost, and the cobalt in the nickel-iron concentrate powder which is not priced is recovered as a high-value product.

Description

Technical Field

[0001] This invention relates to the field of chemical metallurgy, specifically to a method for the synergistic leaching of laterite nickel ore and nickel matte alloy. Background Technology

[0002] The HPAL process is primarily designed for lateritic nickel ore with a magnesium content of less than 5% in limonite. This process offers significant advantages in processing low-grade nickel ore resources that are high in iron and low in magnesium, achieving nickel and cobalt metal recovery rates exceeding 90%. However, currently operating hydrometallurgical plants using the third-generation HPAL process still face the following challenges:

[0003] (1) The HPAL process requires a reaction temperature of 245~270℃ and a pressure of 4.1~5.6MPa, which results in large investment in key process equipment and high equipment operation and maintenance costs.

[0004] (2) The HPAL process requires the magnesium content of the raw ore to be less than 5%, and the raw material adaptability is poor;

[0005] (3) Due to the inherent characteristics of the mineral, the concentration of the slurry entering the reactor cannot exceed 30%, which limits the processing capacity of the system and results in a low concentration of nickel ions in the leachate, which reduces the efficiency of subsequent neutralization and impurity removal and the production of nickel-cobalt products.

[0006] To ensure more efficient, economical, and environmentally friendly development and utilization of laterite nickel ore resources, and to optimize the current utilization status of laterite nickel ore, developing more suitable smelting methods for different types of laterite nickel ore and increasing the production capacity of HPAL process equipment are currently key steps. At the same time, accelerating research on the comprehensive recycling and utilization of all laterite nickel ore resources will be an essential way for enterprises to actively respond to environmental protection requirements. Summary of the Invention

[0007] The purpose of this invention is to provide a method for processing laterite nickel ore with a wider range of applicable raw materials and higher leaching efficiency.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a method for the co-leaching of laterite nickel ore and nickel matte alloy, comprising washing and beneficiation, and a co-leaching step;

[0009] The co-leaching step is specifically divided into two leaching stages, wherein...

[0010] Stage I leaching: Dilute the washed low-magnesium, high-iron, and high-nickel transitional ore slurry to a concentration of 15%–25%, then add 98% sulfuric acid at an acid-to-ore mass ratio of (1.5–2.5):1, and leach at a constant temperature of 85℃ with stirring for 4–6 hours. During the leaching process, add nickel-iron concentrate as a synergist at a mass ratio of 0.1–0.4 times that of the ore in multiple batches for synergistic leaching.

[0011] Second stage leaching: Take the filtrate obtained from the first stage leaching, mix it with limonite to form a slurry, add it to the autoclave, and carry out oxygen pressure reaction.

[0012] Furthermore: the raw ore being washed is a lateritic nickel ore transitional ore, with an iron-nickel ratio >20 for the low magnesium, high iron, and high nickel transitional ore.

[0013] Furthermore: the filtrate obtained from the first stage of leaching contains Ni > 4 g / L, Fe 70-80 g / L, and free sulfuric acid < 50 g / L.

[0014] Furthermore, the filtrate obtained from the second stage leaching has a nickel ion concentration >8 g / L and an Fe ion concentration <10 g / L.

[0015] Furthermore, the second stage leaching also includes a pre-neutralization step. The specific method of this step is to take the second stage leaching solution, add a low-iron, low-nickel, high-magnesium oxide transition mineral, and carry out a neutralization reaction to make full use of the tail acid in the second stage leaching solution, while leaching out nickel.

[0016] Furthermore, in the pre-neutralization process, a low-iron, low-nickel, high-magnesium oxide transition ore is used as the pre-neutralizing agent. The magnesium oxide content of this low-iron, low-nickel, high-magnesium oxide transition ore is >25%, and the iron-nickel ratio is <10.

[0017] Furthermore, the low-magnesium, high-iron transitional ore in the first stage leaching process is replaced with limonite, and after the replacement, the nickel ion concentration in the first stage leaching solution is >3.5 g / L.

[0018] The beneficial technical effects of this invention are:

[0019] (1) The present invention has a wide range of applications. It can wash and classify laterite nickel ore to separate low-iron and high-silicon laterite nickel ore, high-iron and low-magnesium laterite nickel ore, and coarse-grained spinel-type chromite. Based on the characteristics of each type of mineral, targeted leaching processes can be formulated.

[0020] (2). In this invention, fine-grained transitional laterite nickel ore and nickel-iron concentrate are leached together with sulfuric acid under normal pressure. The nickel-cobalt leaching rate is high, and the nickel-cobalt leaching rates of both stage I and stage II are greater than 95%. The leaching solution has a high nickel content, and liquid-solid separation is easy. The leaching residue of stage I can be discarded, and the leaching residue of stage II has a high iron content, which can be utilized as a resource.

[0021] (3) The co-leaching process is used to directly introduce nickel-iron / nickel-iron concentrate into the wet process system through a short process, which greatly increases the value of the valuable metals. The co-leaching solution and limonite-type laterite nickel ore are mixed and sent to the high pressure vessel for oxygen-pressure sulfuric acid leaching. The iron in the system enters the slag in the form of hematite, which increases the utilization value of iron. The oxygen-pressure sulfuric acid leaching achieves a very high nickel-cobalt leaching rate. The nickel-cobalt content in the leaching solution is doubled compared to the nickel-cobalt content in the traditional high pressure leaching solution. The leaching system composed of co-leaching solution and limonite-type laterite nickel ore can control the process of the conversion of ferrous iron to ferric iron in the solution in the high pressure vessel through process parameters, which plays an important role in alleviating the scaling on the inner wall of the high pressure vessel.

[0022] (4) Using high-magnesium and low-iron transition minerals as neutralizing agents not only reduces the discharge of gypsum residue, but also enables the effective recovery and utilization of residual acid in the leachate, thereby achieving further enrichment of nickel in the leachate. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1:

[0024] A method for co-leaching laterite nickel ore and nickel matte alloy includes washing and beneficiation. The laterite nickel ore is a transitional type ore, characterized by a pattern where larger particle sizes correspond to lower nickel and iron content and higher magnesium content, while smaller particle sizes correspond to higher nickel and iron content and lower magnesium content. A slurry with high nickel and iron content and low magnesium content is used for stage I co-leaching. The iron-nickel ratio of this low-magnesium, high-iron, and high-nickel transitional ore is >20. This invention employs a co-leaching step after washing, specifically divided into two stages:

[0025] Stage I leaching: The washed and selected low-magnesium, high-iron, and high-nickel transitional ore slurry is diluted to a concentration of 15%–25%, and then 98% sulfuric acid is added at an acid-to-ore mass ratio of (1.5–2.5):1. Leaching is carried out at a constant temperature of 85℃ with stirring for 4–6 hours. After washing and classifying the transitional laterite nickel ore, the resulting laterite nickel ore can achieve efficient nickel leaching at atmospheric pressure, 85℃, and tailings acid concentration below 40 g / L.

[0026] During the leaching process, nickel-iron concentrate, a synergist, is added multiple times at a ratio of 0.1 to 0.4 times the mass of the ore for synergistic leaching. The resulting filtrate contains Ni > 4 g / L, Fe 70–80 g / L, and free sulfuric acid < 50 g / L.

[0027] In this step, low-magnesium, high-iron, and high-nickel transitional ore is leached in tandem with nickel-iron concentrate. The overall leaching rate of nickel by hot sulfuric acid leaching under normal pressure is very high. The high leaching rate of nickel by tandem leaching is due to the fact that the oxidizing low-magnesium, high-iron, and high-nickel transitional ore and the reducing nickel-iron powder are in the same leaching system and form a galvanic cell reaction. During the reaction, the transfer of electrons has a large electromotive force.

[0028] Stage II Leaching: The filtrate from Stage I leaching is mixed with limonite slurry and added to an autoclave for oxygen-pressure reaction. Iron ions in the solution hydrolyze and precipitate in the autoclave, simultaneously releasing sulfuric acid. The released sulfuric acid then reacts with the limonite. No further acid is added before entering the autoclave. In traditional processes, the limonite slurry and sulfuric acid are piped separately into the autoclave, requiring tantalum for the sulfuric acid pipeline, resulting in extremely high material costs. The nickel ion concentration in the outlet solution is approximately 3 g / L. In this invention, the nickel concentration in the Stage II leaching exceeds 8 g / L, effectively doubling the nickel production capacity of the same autoclave volume. Furthermore, the added atmospheric pressure leaching equipment upstream of the autoclave has significantly lower energy consumption than the investment in the autoclave itself. The filtrate from Stage II leaching contains >8 g / L nickel ions and <10 g / L Fe ions. Example 2:

[0029] A method for co-leaching lateritic nickel ore and nickel matte alloy includes washing and beneficiation, and a co-leaching step, wherein the raw ore for washing and beneficiation is lateritic nickel ore and limonite, and the co-leaching step is specifically divided into two stages of leaching:

[0030] Stage I leaching: Dilute the washed limonite slurry to a concentration of 15%–25%, then add 98% sulfuric acid at an acid-to-ore mass ratio of (1.5–2.5):1. Leach at a constant temperature of 85℃ with stirring for 4–6 hours. During the leaching process, add nickel-iron concentrate as a synergist at a mass ratio of 0.1–0.4 times that of the ore in multiple batches for synergistic leaching. The filtrate obtained after leaching should contain Ni > 3.5 g / L, Fe 70–80 g / L, and free sulfuric acid < 50 g / L.

[0031] In this step, limonite and nickel-iron concentrate are leached together. The overall leaching rate of nickel by hot sulfuric acid leaching under normal pressure is very high. The high leaching rate of nickel by co-leaching is due to the fact that the oxidized limonite and the reduced nickel-iron powder are in the same leaching system and form a galvanic cell reaction. During the reaction, the transfer of electrons has a large electromotive force.

[0032] Second-stage leaching: The filtrate obtained from the first-stage leaching is mixed with limonite slurry and added to an autoclave for oxygen-pressure reaction. Iron ions in the solution hydrolyze and precipitate in the autoclave, simultaneously releasing sulfuric acid. The released sulfuric acid reacts with the limonite, and no further acid is added before entering the autoclave. In traditional processes, the limonite slurry and sulfuric acid are piped separately into the autoclave, requiring tantalum for the sulfuric acid pipeline, resulting in extremely high material costs. The nickel ion concentration in the outlet solution is approximately 3 g / L. In this invention, the nickel concentration in the second-stage leaching exceeds 7 g / L, effectively doubling the nickel production capacity of the same volume autoclave. Furthermore, the added atmospheric pressure leaching equipment upstream of the autoclave has significantly lower energy consumption than the investment in the autoclave itself. The filtrate obtained from the second-stage leaching has a nickel ion concentration >7 g / L and an Fe ion concentration <10 g / L.

[0033] In Examples 1 and 2 above, a pre-neutralization step is included after the second stage leaching. Specifically, this step involves taking the second stage leachate, adding a low-iron, low-nickel, high-magnesium oxide transition mineral, and conducting a neutralization reaction. This ensures full utilization of the tail acid in the second stage leachate while simultaneously leaching nickel. The pre-neutralization process uses a low-iron, low-nickel, high-magnesium oxide transition mineral as a pre-neutralizing agent. This mineral has a higher acid consumption, especially compared to limonite, and because of its lower iron content, it is suitable for atmospheric pressure leaching or as a pre-neutralizing agent to recover residual acid from high-pressure leachate. This avoids the difficulties in iron removal from the leachate and the large consumption of neutralizing agent caused by high iron ion concentration during the neutralization and impurity removal stage. The magnesium oxide content of this low-iron, low-nickel, high-magnesium oxide transition mineral is >25%, and the iron-nickel ratio is <10. In this embodiment of the invention, the larger the particle size of the transition mineral, the lower the iron content and the higher the magnesium content. Through washing and beneficiation, the portion with a magnesium oxide content greater than 25% and an iron content less than 12% is selected to consume the tail acid of the stage II leachate. This not only recycles the tail acid and increases the nickel ion concentration in the leachate, but also reduces the purchase cost of limestone and the amount of gypsum slag discharged by limestone as a neutralizing agent.

[0034] The synergist in the first stage of leaching described in Examples 1 and 2 above can be replaced with either high-grade nickel matte or low-grade nickel matte.

[0035] Through testing, the nickel-cobalt leaching rates of both Section I and Section II in Examples 1 and 2 of the present invention are greater than 95%.

[0036] This invention can be achieved through process improvements:

[0037] (1) The laterite nickel ore is washed and classified to separate low-iron and high-silicon laterite nickel ore, high-iron and low-magnesium laterite nickel ore, and coarse-grained spinel-type chromite. Based on the characteristics of each type of mineral, a targeted leaching process can be formulated.

[0038] (2) The present invention uses atmospheric pressure sulfuric acid leaching for laterite nickel ore, which has a high nickel and cobalt leaching rate, easy liquid-solid separation, and the leaching residue can be discarded.

[0039] (3) Fine-grained transitional laterite nickel ore and nickel-iron concentrate are leached together with sulfuric acid under normal pressure. The nickel and cobalt leaching rate is high, and the final leaching solution contains more than 8 g / L of nickel. Liquid-solid separation is easy. The leaching residue of stage I can be discarded, while the leaching residue of stage II has a high iron content and can be utilized as a resource. In the conventional HPAL process, the nickel ion concentration in the leaching solution is only 3 g / L.

[0040] (4) The co-leaching process is used to directly introduce nickel-iron / nickel-iron concentrate into the wet process system through a short process, which greatly increases the value of the valuable metals. The co-leaching solution and limonite-type laterite nickel ore are mixed and sent to the high pressure vessel for oxygen-pressure sulfuric acid leaching. The iron in the system enters the slag in the form of hematite, which increases the utilization value of iron. The oxygen-pressure sulfuric acid leaching achieves a very high nickel-cobalt leaching rate. The nickel-cobalt content in the leaching solution is doubled compared to the nickel-cobalt content in the traditional high pressure leaching solution. The leaching system composed of co-leaching solution and limonite-type laterite nickel ore can control the process of the conversion of divalent iron to trivalent iron in the solution in the high pressure vessel through process parameters, which plays an important role in alleviating the scaling on the inner wall of the high pressure vessel.

[0041] (5) Using high-magnesium and low-iron transition minerals as neutralizing agents not only reduces the discharge of gypsum residue, but also enables the effective recovery and utilization of residual acid in the leachate, thus achieving further enrichment of nickel in the leachate.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the co-leaching of laterite nickel ore and nickel matte alloy, comprising washing and beneficiation, characterized in that: It also includes a co-leaching step; The raw ore being washed is a laterite nickel ore transitional type ore, with an iron-nickel ratio of >20 for the low magnesium, high iron, and high nickel transitional ore. The co-leaching step is specifically divided into two leaching stages, wherein... Stage I leaching: Dilute the washed low-magnesium, high-iron, and high-nickel transitional ore slurry to a concentration of 15%–25%, then add 98% sulfuric acid at an acid-to-ore mass ratio of (1.5–2.5):1, and leach at a constant temperature of 85℃ with stirring for 4–6 hours. During the leaching process, add nickel-iron concentrate as a synergist at a mass ratio of 0.1–0.4 times that of the ore in multiple batches for synergistic leaching. Second stage leaching: Take the filtrate obtained from the first stage leaching and mix it with limonite-type laterite nickel ore to form a slurry, add it to the autoclave, and carry out oxygen pressure reaction.

2. The method for co-leaching laterite nickel ore and nickel matte alloy according to claim 1, characterized in that: The filtrate obtained from the first stage of leaching contains Ni > 4 g / L, Fe 70-80 g / L, and free sulfuric acid < 50 g / L.

3. The method for co-leaching laterite nickel ore and nickel matte alloy according to claim 1, characterized in that: The filtrate obtained from the second stage leaching has a nickel ion concentration of >8 g / L and a fe ion concentration of <10 g / L.

4. The method for co-leaching laterite nickel ore and nickel matte alloy according to claim 1, characterized in that: The second stage leaching process also includes a pre-neutralization step. The specific method of this step is to take the second stage leaching solution, add a low-iron, low-nickel, high-magnesium oxide transition mineral, and carry out a neutralization reaction to make full use of the tail acid in the second stage leaching solution, while leaching out nickel.

5. The method for co-leaching laterite nickel ore and nickel matte alloy according to claim 4, characterized in that: The pre-neutralization process uses a low-iron, low-nickel, high-magnesium oxide transitional ore as a pre-neutralizing agent. The magnesium oxide content of this low-iron, low-nickel, high-magnesium oxide transitional ore is >25%, and the iron-nickel ratio is <10.

6. A method for co-leaching laterite nickel ore and nickel matte alloy according to any one of claims 1 to 5, characterized in that: In the first stage of leaching, the low-magnesium, high-iron, and high-nickel transitional ore was replaced with limonite, and the nickel ion concentration in the first stage leaching solution was >3.5 g / L after the replacement.

7. The method for co-leaching laterite nickel ore and nickel matte alloy according to claim 1, characterized in that: The synergist in the first stage of leaching can be replaced with either high-grade nickel matte or low-grade nickel matte.