WO2020093365A1 - Wet metallurgy method for treating low-quality lateritic nickel ore using atmospheric pressure and elevated pressure combined acid leaching - Google Patents

Abstract

Disclosed is a wet metallurgy method for treating low-quality lateritic nickel ore using atmospheric pressure and elevated pressure combined acid leaching, comprising the following steps: formulating a transition ore pulp, mixing the heated transition ore pulp and heated concentrated sulfuric acid in a certain proportion, performing an acid leaching reaction, and performing solid-liquid separation after dissolution in water to obtain an atmospheric leaching residue and an atmospheric leaching liquid; formulating a limonite ore pulp, mixing the limonite ore pulp and the atmospheric leaching liquid, heating same, performing pressure leaching under a pressure of 2.0 MPa - 4.0 MPa and a temperature of 220 °C - 240 °C, and then performing solid-liquid separation after cooling to obtain a pressure leaching residue and a pressure leaching liquid; and preparing the pressurized leaching residue into iron powder by using ball pressing and a roasting process.

Description

Hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching Technical field

The invention relates to the technical field of hydrometallurgical technology of laterite nickel ore, in particular to a hydrometallurgical technology of normal pressure and pressurized combined acid leaching to treat low-grade laterite nickel ore.

Background technique

Laterite mines are not the same in all parts of the world due to differences in geographic location, climatic conditions and degree of weathering. A highly weathered layer usually distributes most of the nickel it contains finely in finely divided goethite particles. This layer is usually called limonite, and it generally contains a high proportion of iron and a low proportion of silicon and magnesium. The nickel contained in the lighter weathered layer is generally more contained in various magnesium silicate minerals, such as serpentine. There may be many other nickel-containing silicate minerals in the incompletely weathered zone. The partially weathered high-magnesium zone is usually called saprolite or silicon-magnesium-nickel ore, and it generally contains a low proportion of iron and a high proportion of silicon and magnesium. In some deposits there is another zone, which is usually between limonite and saprolitic soil and mainly contains chlorite clay, called transitional ore. "Low-grade laterite ore" refers to laterite ore without rot mud, that is, laterite ore composed of limonite and transition ore. Normally, limonite is the main component of laterite nickel ore, accounting for 65% -75% of the total laterite; rot soil 15% -25%; transitional mine 10%. The difficulty in recovering nickel and cobalt from laterite nickel ore is that, before chemical treatment to separate metal useful components (such as nickel and cobalt), the useful components of nickel cannot usually be fully enriched by physical means, that is, it cannot be carried out with mineral processing technology. Enrichment, which makes the treatment of laterite nickel ore very costly. And because of the different minerals and chemical composition of limonite, transition ore and saprolite, these ores are generally not suitable for processing with the same processing technology. For decades, we have been looking for ways to reduce the cost of processing laterite nickel ore.

At present, the processing technology of laterite nickel ore can generally be divided into two categories: fire process and wet process. The pyrometallurgical process is suitable for processing saprolite. This process usually only produces ferronickel and cannot recover cobalt, and its application is limited. The hydrometallurgical process is suitable for processing limonite. The hydrometallurgical technology includes high-pressure acid leaching and reduction roasting_ammonia leaching as well as recent atmospheric pressure leaching and heap leaching processes. The heap leaching technology has a low leaching rate and is only suitable for processing high-magnesium laterite ore; the reduction roasting-ammonia leaching process is less used due to the higher energy consumption and long process flow; the atmospheric pressure acid leaching technology is simple and does not require An expensive autoclave is used, but the acid consumption is large to completely dissolve the minerals, and the leaching solution contains various metal ions, which complicates the subsequent leaching and separation process. The high-pressure acid leaching (HPAL) process uses sulfuric acid to leach the laterite nickel ore under high temperature (250 ° C) and high pressure (50 MPa). Under high temperature and high pressure conditions, the metal minerals in the ore are almost completely dissolved. Dissolved iron rapidly hydrolyzes to hematite (Fe ₂ 0 ₃ ) precipitates at the high temperature used, nickel, cobalt, etc. remain in solution, and after cooling, the leaching residues containing iron and silicon are concentrated by a series of washings, ie The so-called countercurrent decantation (CCD) circuit is concentrated and separated from the solution containing nickel and cobalt. Therefore, the main purpose of the leaching process is achieved-separating nickel from iron.

The advantages of the existing high-pressure acid leaching (HPAL) process are: high leaching rate of nickel and cobalt; fast reaction speed and short reaction time; theoretically, during the acid leaching process, iron does not consume sulfuric acid and the hydrolysate is hematite (Fe ₂ 0 ₃ ) Precipitation. However, the disadvantages of the high-pressure acid leaching (HPAL) process are also very prominent: first, it requires a complex high-temperature, high-pressure autoclave and related equipment, and its installation and maintenance are very expensive; second, the high-pressure acid leaching (HPAL) process consumes Sulfuric acid is more than that required to stoichiometrically dissolve non-ferrous metal components in the ore. Since most of the sulfate ions provided by sulfuric acid linked to form a hydrogen sulfate ion (HSO ₄ ^-) acid leaching under high pressure conditions. That is to say, sulfuric acid releases only one proton (H +) from the interpretation under high-pressure acid leaching conditions. When the leaching solution is cooled and neutralized, the bisulfate ion is decomposed into sulfate (SO ₄ ^2- ) and another proton. Therefore, the latter proton (acid) is not fully used for leaching, and it causes excessive sulfuric acid to be neutralized in the subsequent treatment and consumes the neutralizing agent; third, the HPAL process is limited to processing mainly raw materials of limonite, because The presence of transition mines will lead to a substantial increase in sulfuric acid consumption. This is caused by the high content of magnesium in the saprolite. Fourth, the autoclave is easy to scale during the operation of the HPAL process. It needs to be shut down and cleaned regularly, and the operating rate is low. Fifth, the amount of leaching slag is large, and it is silicon and Iron mixed slag cannot be developed and utilized cost-effectively.

Therefore, a new wet smelting process technology was explored to extract nickel, cobalt, and iron from low-grade laterite nickel ore, to achieve the goal of reducing acid consumption, improving the leaching rate of nickel-cobalt-iron, and iron recovery and utilization. Imperative.

Summary of the invention

The purpose of the present invention is to solve the technical problems existing in the prior art, and to provide a hydrometallurgical technology for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching to carry out sulfuric acid on the transition ore components in laterite nickel ore Method for recovering nickel, cobalt and iron by normal pressure leaching and pressure leaching of limonite components with normal pressure leaching solution.

In order to achieve the above object, the present invention adopts the following technical solution: a hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching, characterized in that it includes the following steps:

(a) Prepare the transition ore pulp, mix the heated transition ore pulp and the heated concentrated sulfuric acid at a certain ratio, an acid leaching reaction occurs, and after the water is dissolved, the solid-liquid separation obtains the atmospheric leaching slag and atmospheric pressure leaching liquid;

(b) Preparation of limonite ore slurry, mixing the limonite ore slurry and the normal pressure leaching solution, heating, and pressure leaching under the conditions of pressure 2.0MPa-4.0Mpa, temperature 220 ℃ -240 ℃, After the temperature is lowered, solid-liquid separation is performed to obtain pressure leaching residue and pressure leaching liquid;

(c) Pressing the ball and roasting the slag under pressure to make fine iron powder.

Specifically: (a) Prepare a transition ore pulp with a concentration of 30-60% and heat it to 60 ℃ -80 ℃; heat concentrated sulfuric acid at 120 ℃ -180 ℃ at the same time. The transitional slurry and concentrated sulfuric acid after heating shall be (2.0-2.3): 1 Proportionally added to the acid leaching reactor, leaching reaction occurs, nickel, cobalt, iron and other metal elements in the transition ore are dissolved in the form of metal ions, silicon and other insoluble materials are produced in the form of solid slag; The material enters into the acid leaching reverse tank, and under the stirring condition of the acid leaching reaction tank, the acid leaching reaction of nickel, cobalt, iron and other metal elements is continued to be fully carried out, the reaction time is 10-30 min; Slag and normal pressure leaching solution; (b) Preparation of 30-60% limonite ore slurry, mixing the limonite slurry and normal pressure leaching solution, and using the high temperature reaction produced by the iron removal reactor in the iron removal heat exchanger The residual heat of the material, the temperature is heated to 160-200 ℃, and then directly heated to 220-250 ℃ with medium-pressure steam in the horizontal heater, and then enters the iron removal reactor, the pressure is 2.0MPa-4.0Mpa, the temperature is Pressure leaching under the condition of 220 ℃ -240 ℃ for 0.5-1.5 hours, normal pressure leaching Fe ³⁺ in the hydrolysis of Fe ₂ O ₃ precipitated and then releasing the acid leaching limonite; 360-degree rotation in addition to iron the reactor, the reactor feed is provided an inverted copy board, to achieve thorough mixing and uniform concentration, reaction sufficiently There is no dead angle, which solves the problems of scaling and partial reaction in the existing process. The high-temperature iron removal liquid produced by the iron removal reactor is cooled to below 100 ° C in the iron removal heat exchanger, and solid-liquid separation is performed to obtain pressurized leaching slag and pressurized leaching liquid; the iron removal reactor rotates 360 degrees and is hot and cold The materials are heated inversely and indirectly, the heat exchange efficiency is high, and the flow rate of the hot and cold materials is stable, which solves the problems of local scaling and realizes the recovery and utilization of the system's waste heat. (c) For the pressure leaching slag, iron powder pellets are made by pressing balls and roasting technology, and exported to iron and steel plants.

Further, the concentrated sulfuric acid in the step (a) can be adjusted to strong acids such as nitric acid and hydrochloric acid.

Further, the mass ratio of the transition ore pulp and limonite ore pulp in the steps (a) and (b) is 1: 2-1: 3.

Further, the atmospheric pressure leaching slag produced in the step (a) is silicon slag, which realizes the separation of silicon and iron compared with the traditional process, and increases the content of the pressure leaching slag iron.

Further, the acid leaching reactor realizes the efficient and rapid leaching reaction of laterite nickel ore and sulfuric acid; the iron removal reactor realizes the rapid generation of iron slag in laterite nickel ore; the iron removal heat exchanger realizes the cold and hot materials in the iron removal process Reverse heat energy exchange, heat recovery and utilization; horizontal heater realizes further increase of material temperature before entering the reactor.

Further, the pressure leaching slag obtained in the step (c) is iron slag, and the iron content of the iron ore concentrate can be achieved from 61% to 65% through the briquetting and roasting technology, which satisfies the raw material of iron concentrate powder in the steel plant The requirement solves the problem that the existing process iron slag cannot be recycled.

among them:

During the acid leaching process of the transition ore in the acid leaching reactor, the transition ore slurry and a sufficient amount of concentrated sulfuric acid are quickly and fully mixed, and the metals (nickel, cobalt, iron, magnesium, chromium, aluminum, etc.) in the transition ore and the sulfuric acid react quickly This produces metal sulfates.

In the acid leaching reaction tank, under the stirring condition of the acid leaching reaction tank, continue to carry out the acid leaching reaction of nickel, cobalt, iron and other metal elements fully, the reaction time is 10-30min, a large amount of reaction heat makes the reaction of the material completely complete, Silica and very small amounts of unreacted iron and non-ferrous metals form leaching residues.

In the process of water-soluble and solid-liquid separation of normal pressure acid leaching materials, add water that can ensure that all metal sulfates are dissolved and stir to dissolve all metal sulfates into the solution. After solid-liquid separation and filter residue washing, atmospheric pressure leaching residue, Atmospheric leaching solution.

In the process of leaching limonite in the atmospheric pressure leaching solution, the atmospheric pressure leaching solution and the limonite slurry are added to the iron removal reactor for pressure leaching, and Fe ^{3+ is} hydrolyzed to Fe ₂ O ₃ hematite precipitation and the acid is released and the brown Iron ore, the reaction pressure is 2MPa-4.0Mpa, the reaction temperature is 220 ℃ -240 ℃, not only can ensure that the hydrolysate of iron ions is hematite, but also has a fast hydrolysis rate and a high nickel and cobalt leaching rate and leaching rate .

The pressure leaching material is cooled and solid-liquid separation is performed to obtain pressure leaching slag and pressure leaching liquid; the main component of the pressure leaching slag after washing is Fe ₂ O ₃ hematite, and iron concentrate is produced through ball pressing and roasting process. It is exported to steel mills as a raw material for production.

Compared with the prior art, the present invention has the following beneficial effects:

1. A hydrometallurgical technology that combines low-grade laterite nickel ore with normal pressure and pressurized acid leaching has been implemented. Sulphuric acid leaching of transition ore components in laterite nickel ore and atmospheric pressure leaching solution for limonite components The method of recovering nickel, cobalt and iron by pressure leaching overcomes the deficiencies of the traditional methods of fire and wet processes. Compared with the high-pressure acid leaching (HPAL) process, the pressure leaching of the present invention is carried out at 2.0 MPa-4.0 MPa, and the pressure is much lower than the high-pressure acid leaching conditions of 4.5 MPa-5.0 MPa. The normal pressure leaching time of the invention is 1-12 minutes, and the existing normal pressure acid leaching time is usually 240 minutes to 2400 minutes. The corresponding investment of the normal pressure acid leaching equipment of the present invention is much smaller than the investment of the existing normal pressure acid leaching equipment.

2. The sulfuric acid consumption of the present invention is not only much lower than the acid consumption of the existing atmospheric acid leaching, but also lower than the acid consumption of the existing high-pressure acid leaching. The acid consumption of the existing atmospheric acid leaching is 2.57- 3.33 times, the acid consumption of the existing high-pressure pickling is 1.39-1.71 times that of the present invention. In the present invention, the sulfuric acid and iron added at one time in the normal pressure leaching stage of the transition mine react to produce ferric sulfate. In the pressure leaching stage of limonite, no additional sulfuric acid is needed, but instead rely on Fe ³⁺ hydrolysis to precipitate hematite The protons (acids) released to leach limonite can greatly reduce the consumption of subsequent neutralizers. At the same time, it avoids that the slurry and concentrated sulfuric acid in the existing high-pressure acid leaching process are directly added to the autoclave, and the local concentration of sulfuric acid is high, and it is easy to form scales such as basic iron sulfate and alum.

3. The existing high-pressure acid leaching process and normal pressure acid leaching process have a large amount of leaching slag. The leaching slag is a mixed slag of silicon and iron, which cannot be used to develop and utilize iron ore and a small amount of silicon as leaching residues. The present invention effectively separates the atmospheric leaching slag and the pressure leaching slag, that is, the pressure leaching slag has a high iron content. After pressing and roasting, the iron concentrate containing 61-65% iron can be obtained and directly exported to the iron plant .

4. The nickel leaching rate of the present invention is not only much higher than that of the existing normal pressure acid leaching, but also higher than the existing high pressure acid leaching nickel leaching rate. The nickel leaching rate of the existing normal pressure acid leaching is 70-85%, the nickel leaching rate of the existing high pressure acid leaching is 90-93%, and the leaching rate of the nickel, cobalt and iron of the present invention is above 96%.

BRIEF DESCRIPTION

FIG. 1 is a schematic flowchart of the present invention.

detailed description

The present invention will be further described below with reference to specific embodiments.

Example 1

Table 1-1 Main components of ore

Ore type Ni (%) Co (%) Fe (%) MgO (%) SiO ₂ (%)) Limonite 1.13 0.20 48.76 0.23 3.58 Transition mine 1.80 0.35 32.24 2.07 24.45

Take 500Kg of transition ore (dry) and add 500Kg of water to make transition ore slurry, prepare 500Kg of concentrated sulfuric acid with 98% mass fraction, heat the transition ore slurry to 60 ℃, concentrated sulfuric acid to 200 ℃, then heat it with mortar pump and concentrated sulfuric acid pump The late transition pulp and concentrated sulfuric acid are added to the feed port of the acid leaching reactor simultaneously. After rapid mixing, the transition pulp and concentrated sulfuric acid are forced to flow into the acid leaching reactor for rapid reaction to dissolve the soluble non-ferrous metals and soluble iron. The reaction takes 1 minute Then the reaction materials are pushed out of the acid leaching reactor. Reduce the temperature to below 60 ℃, simply crush the reaction material of the honeycomb solid paste and pour it into a water immersion tank, add 1500Kg of water, stir for 30 minutes to dissolve the water, and pump the resulting slurry into the frame filter Solid-liquid separation and filter residue washing were performed to obtain 185 kg (dry) of atmospheric leaching residue and 1480 L of atmospheric leaching solution. The components of the atmospheric leaching residue and atmospheric pressure leaching solution (B1) are shown in Table 1-2 and Table 1-3.

Take 30Kg limonite (dry), add 60L of washing solution to prepare limonite slurry, heat the limonite slurry to 95 ℃, add it to the iron removal reactor, and then add the one heated to 95 ℃ in the iron removal reactor Atmospheric pressure leaching solution (B1) makes the final pH value of the reaction material 0.5, and controls the temperature to heat, leaching under pressure at 2 MPa and 240 ℃ for 50 minutes, Fe ³⁺ in the atmospheric leaching solution is hydrolyzed to hematite Precipitate and release acid and then leaching limonite; after cooling to 85 ℃, remove the reaction slurry from the iron removal reactor for solid-liquid separation and wash the filter residue, to obtain pressure leaching residue 28Kg (dry), pressure leaching solution 76L, add After the non-nickel and cobalt impurities are removed by the pressure leaching solution, nickel and / or cobalt can be recovered by an immediate method. The components of the pressure leaching residue and pressure leaching solution are shown in Table 1-4 and Table 1-5.

Taking 300g of pressure leaching slag for ball pressing and roasting to obtain 295g of iron concentrate.

Table 1-2 Statistical Table of Atmospheric Pressure Leaching Residue Composition

ingredient Ni Co Fe Mg Si content(%) 0.11 0.013 24.1 2.8 18.2

Table 1-3 Statistical Table of Atmospheric Pressure Leachate Composition

ingredient Ni Co Fe Mg Content (g / L) 3.9 0.2 98.76 4.32

Table 1-4 Statistical Table of Pressure Leaching Residue Composition

ingredient Ni Co Fe Mg Si content(%) 0.04 0.0013 58.46 0.13 1.49

Table 1-5 Statistical Table of Pressure Leachate Composition

ingredient Ni Co Fe Mg Content (g / L) 3.71 0.29 2.38 2.2

The leaching rates of normal pressure acid leaching nickel, cobalt, and iron are: 97.8%, 96.1%, and 96.5%, respectively.

The leaching rates of nickel and cobalt under pressure leaching are: 97.5% and 96.2%, respectively.

Iron recovery rate> 96%.

Sulfuric acid consumption: 250Kg · sulfuric acid / t · ore.

The iron content of iron concentrate is> 61%.

Example 2

Follow the steps of Example 1 to organize the operation of Example 2 and the results of the example of the limonite in Table 2-1

Table 2-1 Main components of ore

Ore type Ni (%) Co (%) Fe (%) Mg (%) Si (%)) Limonite 1.07 0.22 43.79 0.14 2.67

Table 2-2 Statistical Table of Composition of Atmospheric Pressure Leaching Residue

ingredient Ni Co Fe Mg Si

content(%) 0.22 0.043 17.96 1.37 11.75

Table 2-3 Statistical Table of Atmospheric Pressure Leachate Composition

ingredient Ni Co Fe Mg Content (g / L) 3.23 0.036 102.01 0.21

Table 2-4 Statistical Table of Pressure Leaching Residue Composition

ingredient Ni Co Fe Mg Si content(%) 0.026 0.0017 59 0.17 0.06

Table 2-5 Statistical Table of Pressure Leachate Composition

ingredient Ni Co Fe Mg Content (g / L) 5.84 0.12 6.72 1.04

The leaching rates of normal pressure acid leaching nickel, cobalt, and iron are: 97.5%, 96.3%, and 96.3%, respectively.

The pressure leaching rates of nickel and cobalt are 98.0% and 96.7%, respectively.

Iron recovery rate> 96%.

Sulfuric acid consumption: 280Kg · sulfuric acid / t · ore.

The iron content of iron concentrate is> 61%.

Claims (8)

A hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching is characterized by the following steps: (a) Prepare the transition ore pulp, mix the heated transition ore pulp and the heated concentrated sulfuric acid at a certain ratio, an acid leaching reaction occurs, and after the water is dissolved, the solid-liquid separation obtains the atmospheric leaching slag and atmospheric pressure leaching liquid; (b) Preparation of limonite ore slurry, mixing the limonite ore slurry and the normal pressure leaching solution, heating, and pressure leaching under the conditions of pressure 2.0MPa-4.0Mpa, temperature 220 ℃ -240 ℃, After the temperature is lowered, solid-liquid separation is performed to obtain pressure leaching residue and pressure leaching liquid; (c) Pressing the ball and roasting the slag under pressure to make fine iron powder. The hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching according to claim 1, characterized in that the concentration of the transition ore pulp in step (a) is 30% -60 %, The transitional slurry heated to 60 ° C-80 ° C and concentrated sulfuric acid heated to 120 ° C-180 ° C are mixed in a ratio of (2.0-2.3): 1. The hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching according to claim 1, characterized in that the concentration of the limonite pulp in step (b) is 30% -60%. The hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurized acid leaching according to claim 1, characterized in that: the step of pressurized leaching in step (b) is 0.5-1.5 hour. A hydrometallurgical method for treating low-grade laterite nickel ore by combined atmospheric and pressurized acid leaching according to claim 1, characterized in that: the concentrated sulfuric acid in step (a) is replaced by nitric acid and hydrochloric acid . A hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching according to claim 1, characterized in that: in the steps (a) and (b), the transition slurry and brown iron The mass ratio of ore pulp is 1: 2-1: 3. The hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurized acid leaching according to claim 1, characterized in that: the normal pressure leaching slag produced in the step (a) is silicon Slag. The hydrometallurgical method for treating low-grade laterite nickel ore by combining normal pressure and pressurization with acid leaching according to claim 1, characterized in that the pressure leaching slag obtained in step (c) is iron slag, Through ball pressing and roasting technology, the iron content of iron concentrate is 61% -65%.

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