CN103614571A - Combined leaching process of laterite-nickel ore - Google Patents

Abstract

A combined leaching process of lateritic nickel ore. Limonite-type laterite nickel ore is crushed and graded, and then concentrated sulfuric acid is added for a period of self-heating leaching under normal pressure. The final slurry is sent into the autoclave at the same time, and the serpentine is leached out by the first stage of atmospheric pressure leaching residual acid and the acid generated by iron precipitation in the autoclave. Alternatively, the fine-grained ore of the mixed laterite nickel ore is classified and then added with concentrated sulfuric acid for a period of stirring and leaching under normal pressure. Coarse-grained ore is leached by atmospheric pressure leaching residual acid and acid generated by iron precipitation in autoclave. Therefore, the present invention has no special requirements on ore type and grade, has wide adaptability of raw materials, reduces investment, energy consumption and production cost, and has a simple process. The recovery rates of Ni and Co in the whole process are respectively >90% and >88%, which are higher than the existing ones. Treatment methods in non-high pressure acid leaching techniques.

Description

A kind of technology of combined leaching of laterite nickel ore

technical field

The invention relates to a process for combined leaching of laterite nickel ore, that is, a process for extracting nickel and cobalt from laterite nickel ore, in particular to a process for extracting intermediate products of nickel and cobalt concentrates from nickel laterite ore.

technical background

The development of the global economy has led to a steady increase in the demand for nickel. With the depletion of nickel sulfide ore resources, laterite nickel ore, which accounts for 70% of the world's nickel resources, has become the main source of nickel.

Laterite nickel ore is an oxide ore rich in nickel, and its nickel reserves account for about 70% of the total land-based nickel reserves on the earth. At present, the laterite nickel ore treatment processes at home and abroad are mainly divided into pyrotechnics and wet processes. The pyrotechnic process mainly includes four types: (1) RKEF smelting ferronickel; (2) blast furnace smelting nickel-containing pig iron; (3) blast furnace smelting matte; (4) rotary kiln reduction-mining process. Due to high energy consumption, the pyrotechnic process is only suitable for processing laterite ore with high nickel content (nickel content greater than or equal to 1.5%), and the associated valuable metal cobalt cannot be recovered. The wet process mainly includes three types: (1) reduction roasting-ammonia leaching; (2) high pressure acid leaching; (3) atmospheric pressure acid leaching.

Ammonia leaching is suitable for ores with high magnesium oxide content. The recovery rate of nickel in the whole process is 70% to 80%, and the recovery rate of cobalt is 40% to 50%. High-pressure acid leaching is used for ores with high iron content and low magnesium oxide. The recovery rate of nickel by this method is 90% to 92%, and the recovery rate of cobalt is 88% to 90%. The reduction roasting-ammonia leaching process has been gradually eliminated globally due to its high energy consumption, low recovery rate and high environmental protection pressure, and it is rarely used in new nickel laterite mine projects.

In recent years, the hydrometallurgical technology of nickel laterite ore in the world has developed rapidly, especially the high-pressure acid leaching process, which has a high nickel-cobalt leaching rate (the leaching rate of nickel-cobalt is as high as 97% and more than 95%), and the impurity content of the leached liquid Low, the follow-up treatment process is relatively simple, and high-quality nickel-cobalt concentrates can be obtained. It has become the most important treatment process for nickel laterite ore in recent years.

However, the high-pressure acid leaching process has shortcomings such as high equipment requirements, high production and operation costs, and large project investment.

Contents of the invention

The object of the present invention is to provide a process for combined leaching of laterite nickel ore, which has wide ore adaptability, low production cost, simple process flow, high recovery rate, and can extract nickel and cobalt from laterite nickel ore in an environmentally friendly manner.

Another object of the present invention is to provide a process for combined leaching of laterite nickel ore, which has a wide range of applicable grades, simple process, low energy consumption and cost, and high recovery rate.

The invention is realized through the following technical scheme: the laterite nickel ore is processed by the method of "normal pressure leaching-pressure leaching-after leaching pulp neutralization and impurity removal-nickel-cobalt precipitation" to produce nickel-cobalt enrichment. Include the following steps:

(1) Atmospheric pressure leaching: Limonite-type laterite nickel ore is crushed and ground, or fine-grained mixed laterite nickel ore is added with concentrated sulfuric acid for atmospheric pressure stirring and self-heating leaching;

(2) Pressure leaching: serpentine-type laterite nickel ore or coarse-grained mixed laterite nickel ore is crushed and ground, mixed with the pulp after the first stage of normal pressure leaching, and then sent to the autoclave for the second stage of pressure leaching ;

(3) Neutralization and removal of impurities after leaching: After pressure leaching, limestone is added to the slurry, and _SO2 and air mixed gas or hydrogen peroxide is added for neutralization and removal of impurities;

(4) Cobalt and nickel precipitation: After the neutralized pulp is subjected to CCD countercurrent dense washing, NaOH is added to the washed liquid to neutralize the precipitation to obtain nickel and cobalt enrichment.

In step (1), the limonite-type laterite-nickel ore is crushed and ground and then directly added to sulfuric acid for stirring and leaching under normal pressure; According to the different properties of raw materials, it can be used to process limonite-type laterite-nickel ore, serpentine-type laterite-nickel ore, or mixed-type laterite-nickel ore, and has wide adaptability to raw materials. Atmospheric pressure stirring leaching controls the amount of concentrated sulfuric acid to 0.5-1.5t/t ore, the leaching cycle is 1-8h, the leaching temperature is 70-120°C, and the initial pulp concentration is 20-50%. Under these conditions, the leaching rate of Ni is >97%, and the leaching rate of Co is >95%. , Mg, Al, Ni, Co, Mn, Zn, Cu, Ca, Cr and other oxides also partially undergo neutralization reactions and enter the solution. The main chemical reaction equation is as follows:

NiO+H ₂ SO ₄ =NiSO ₄ +H ₂ O (1)

CoO+H ₂ SO ₄ =CoSO ₄ +H ₂ O (2)

2FeOOH+3H ₂ SO ₄ =Fe ₂ (SO ₄ ) ₃ +4H ₂ O (3)

FeO+H ₂ SO ₄ =FeSO ₄ +H ₂ O (4)

Al ₂ O ₃ +3H ₂ SO ₄ =Al ₂ (SO ₄ ) ₃ +3H ₂ O (5)

MgO+H ₂ SO ₄ =MgSO ₄ +H ₂ O (6)

MnO+H ₂ SO ₄ =MnSO ₄ +H ₂ O (7)

ZnO+H ₂ SO ₄ =ZnSO ₄ +H ₂ O (8)

CuO+H ₂ SO ₄ =CuSO ₄ +H ₂ O (9)

Cr ₂ O ₃ +3H ₂ SO ₄ =Cr ₂ (SO ₄ ) ₃ +3H ₂ O (10)

In step (2), the coarse-grained ore of serpentine-type laterite nickel ore or mixed laterite-nickel ore is crushed and ground, mixed with the slurry after normal pressure leaching, and then added to the autoclave. The residual sulfuric acid in the pulp and the acid newly generated by iron precipitation in the autoclave are used to leach serpentine or mixed laterite nickel ore coarse-grained ore, and at the same time achieve the purpose of laterite nickel ore leaching, neutralization and iron removal, and minimize the consumption of sulfuric acid ; According to the different properties of raw materials, the newly added ore in the pressure leaching section can be serpentine-type laterite-nickel ore, or coarse-grained mixed-type laterite-nickel ore. Pressure leaching control The ratio of the amount of ore added in the second stage of pressure leaching to the amount of ore in the first stage of normal pressure leaching is 1:0.25~1:4, the leaching cycle is 1~8h, the leaching temperature is 120~180℃, and the leaching pressure is 3~8atm. The initial pulp concentration of adding ore is 20-50%. Under these conditions, the leaching rate of Ni is >93%, the leaching rate of Co is >90%, and the concentration of Fe in the solution is <4g/L. In the process of pressure leaching, after the first stage of leaching, the pulp Fe3+ is hydrolyzed and precipitated into the slag, and the second stage is added to the valuable metal Ni in the ore, and the oxides of Co and sulfuric acid undergo a neutralization reaction and enter the solution. At the same time, other impurity elements such as Mg, Al, Ni , Co, Mn, Zn, Cu, Ca, Cr and other oxides also partially undergo neutralization reactions and enter the solution. The main chemical reaction equation is as follows:

NiO+H ₂ SO ₄ =NiSO ₄ +H ₂ O (11)

CoO+H ₂ SO ₄ =CoSO ₄ +H ₂ O (12)

Fe ₂ (SO ₄ ) ₃ +4H ₂ O=2FeOOH↓+3H ₂ SO ₄ (13)

Fe ₂ (SO ₄ ) ₃ +3H ₂ O=Fe ₂ O ₃ ↓+3H ₂ SO ₄ (14)

Al ₂ O ₃ +3H ₂ SO ₄ =Al ₂ (SO ₄ ) ₃ +3H ₂ O (15)

MgO+H ₂ SO ₄ =MgSO ₄ +H ₂ O (16)

MnO+H ₂ SO ₄ =MnSO ₄ +H ₂ O (17)

ZnO+H ₂ SO ₄ =ZnSO ₄ +H ₂ O (18)

CuO+H ₂ SO ₄ =CuSO ₄ +H ₂ O (19)

Cr ₂ O ₃ +3H ₂ SO ₄ =Cr ₂ (SO ₄ ) ₃ +3H ₂ O (20)

In step (3), limestone slurry is added to the slurry after pressure leaching, and a mixed gas of SO ₂ and air or H ₂ O ₂ is introduced to neutralize and remove impurities. Remove impurities by oxidation and neutralization, and the concentration of iron ions in the pulp after neutralization is less than 0.1g/L. The reaction conditions for pressurized leaching pulp neutralization and impurity removal are: reaction temperature 50-100°C, reaction time 0.5-6h, control solution end point pH 2-5, liquid Fe<0.1g/L after impurity removal, Ni, Co loss rate<2 %, the main chemical reaction equation is as follows:

CaCO ₃ +H ₂ SO ₄ =CaSO ₄ ↓+H ₂ O+CO ₂ ↑ (21)

As the reaction progressed and the pH value increased, some Fe, Al, and Cr ions underwent hydrolysis and precipitation reactions. The main chemical reaction equation is as follows:

Fe ₂ (SO ₄ ) ₃ +3H ₂ O=Fe ₂ O ₃ ↓+3H ₂ SO ₄ (22)

Al ₂ (SO ₄ ) ₃ +6H ₂ O=2Al ₂ O ₃ ↓+3H ₂ SO ₄ (23)

Cr ₂ (SO ₄ ) ₃ +3H ₂ O=Cr ₂ O ₃ ↓+3H ₂ SO ₄ (24)

In step (3), after neutralization and removal of impurities, the ore pulp enters the CCD for countercurrent dense washing, and the recovery rate of Ni and Co is >98%. 99.5%. The main chemical reaction equation is as follows:

(1+a)NiSO ₄ +2NaOH=Na ₂ SO ₄ +Ni(OH) ₂ ·aNiSO ₄ ↓ (25)

(1+b)CoSO ₄ +2NaOH=Na ₂ SO ₄ +Co(OH) ₂ bCoSO ₄ ↓ (26)

The solution after nickel and cobalt precipitation is mixed with CCD countercurrent dense washing bottom flow, and then neutralized and precipitated with lime slurry to precipitate Mg and a small amount of residual Fe, Mn, Ni, Co, etc. in the solution, and then sent to the tailings pond for clarification. After clarification, the liquid is returned to the main The production system is recycled.

Compared with the pyrotechnic process and wet process in the prior art, the method of the present invention can simultaneously process limonite-type laterite-nickel ore and serpentine-type laterite-nickel ore according to the difference in raw material properties, and can also process mixed-type laterite-nickel ore nickel ore.

Therefore, the present invention has no special requirements on ore type and grade, and has wide adaptability of raw materials. Compared with traditional atmospheric pressure leaching, the present invention can greatly increase the leaching rate of valuable metals, reduce sulfuric acid consumption and the impurity content in the pulp after leaching. Compared with pressure leaching, it can greatly reduce the reaction temperature and pressure in the pressure leaching section, and reduce investment, energy consumption and production costs.

In addition, the slag after neutralization in the method of the present invention can be greened and reclamated on the spot, greatly reducing the discharge of tailing slag, waste gas and waste water, and being environmentally friendly.

The Ni and Co recovery rates of the whole process of the present invention are respectively >90% and >88%, and the metal recovery rate is high.

Description of drawings

Fig. 1 is the overall flowchart of laterite-nickel ore combined leaching process according to the present invention;

Fig. 2 is a structural principle diagram of the laterite nickel ore combined leaching system according to the present invention.

Detailed ways

The present invention will be further described below in conjunction with the examples.

As shown in Figure 1-2, according to a kind of combined leaching system of laterite nickel ore of the present invention, the normal pressure leaching tank 10 of limonite-type laterite nickel ore section 10 and the serpentine slurry transition tank 20 are connected in parallel with the mixing tank 30, The mixing tank 30, the second-stage pressure leaching tank 40, and the pulp neutralization tank 50 after leaching are successively connected; the first-stage atmospheric pressure leaching tank 10 is provided with a limonite-type lateritic nickel ore inlet 11 and a concentrated sulfuric acid inlet 12; The striatum pulp transition tank 20 is provided with a serpentine pulp inlet 21 and a water inlet 22; the second-stage pressurized leaching tank 40 is connected to the ventilation source 41; the pulp neutralization tank 50 is connected to the tailings pond 60 through the bottom flow thickener Connected; the slurry neutralization tank 50 is also communicated with the cobalt-nickel sedimentation tank 80 through the supernatant pool 70; the cobalt-nickel sedimentation tank 80 is communicated with the tail liquid treatment device 100 through the tail liquid thickener 90, and is connected with the nickel-cobalt sedimentation tank 80 through the tail liquid thickener 91 The enrichment container 99 communicates.

In the upstream of the normal pressure leaching tank 10 of the limonite type laterite nickel ore stage, one, several or all of the crusher, ball mill, particle screening machine, particle thickener, and limonite type laterite nickel ore transition tank are provided (see reference number 13).

A section of slurry transition tank 14 is provided between the first-stage atmospheric pressure leaching tank 10 and the mixing tank 30 of limonite-type lateritic-nickel ore.

A diaphragm pressure pump 35 is provided between the mixing tank 30 and the second-stage pressure leaching tank 40 .

Between the second-stage pressurized leaching tank 40 and the leached pulp neutralization tank 50, a flash tank, a defoaming tank and a second-stage leaching pulp storage tank (see reference numeral 45) are arranged.

The pulp neutralization tank 50 after leaching is provided with a neutralizer inlet 51 and a secondary leached pulp inlet 52 .

The underflow thickener 55 is provided with a flocculant inlet 53 and a washing water inlet 54 .

The cobalt nickel precipitation tank 80 is provided with a supernatant liquid inlet 81 and a precipitant inlet 82 .

Example 1

Take 200g (dry basis) of limonite-type lateritic nickel ore (Ni1.17%, Co0.10%, Fe43.05%, MgO1.43%), add water to adjust the slurry concentration to 33%, and use ₉₈ % _H2SO4 The solution is self-heating and stirring leaching under normal pressure. The leaching temperature is 95°C. After 6 hours of leaching, the leaching rates of nickel and cobalt reach 98.11% and 96.48%, respectively, and the total acid consumption is 224.48g, which is 1.1t acid/t ore.

Take 200g (dry basis) serpentine-type laterite nickel ore (Ni1.54%, Co0.02%, Fe5.53%, MgO32.0%), adjust the slurry concentration to 33%, and mix it with the slurry after normal pressure leaching After that, it is sent to the pressure kettle for two-stage pressure leaching. The leaching temperature is 150°C for 2 hours, the leaching pressure is 0.45MPa, the total leaching rates of nickel and cobalt reach 93.61% and 91.39% respectively, and the total acid consumption is 550kg/t ore . The Fe content of the solution after leaching was 4.01g/L.

Compared with traditional crafts:

(1) One-stage atmospheric pressure leaching process

Take 400g of mixed laterite nickel ore (Ni1.36%, Co0.06%, Fe24.29%, MgO16.72%), add water to adjust the slurry concentration to 33%, and use 98% H ₂ SO ₄ solution under normal pressure Self-heating and stirring leaching, the leaching temperature is 95°C, after 6 hours of leaching, the leaching rates of nickel and cobalt are 83.11% and 80.79% respectively, and the acid consumption is 220g, which is 550kg acid/t ore. The Fe content of the solution after leaching was 113.55g/L.

Compared with the traditional atmospheric pressure leaching process, under the same acid consumption conditions, the new combined leaching process increases the nickel and cobalt leaching rates by 10.50% and 10.60% respectively compared with the traditional one-stage atmospheric pressure leaching process, and the concentration of liquid iron after leaching decreases by 109.54g/ L, the new process greatly reduces the burden of the subsequent iron removal process.

(2) One stage pressure leaching process

Take 400g of mixed laterite nickel ore (Ni1.36%, Co0.06%, Fe24.29%, MgO16.72%), add water to make the slurry concentration 33%, add water to make the slurry concentration 33%, use 98% _H2 The SO ₄ solution was leached under pressure in an autoclave, the leaching temperature was 250°C, and the leaching pressure was 4.5MPa. After 1 hour of leaching, the leaching rates of nickel and cobalt reached 97.35% and 96.01% respectively, and the acid consumption was 210g, resulting in 525kg acid/t ore . The Fe content of the solution after leaching was 1.55g/L.

Compared with the traditional pressure leaching process, under the condition of slightly higher acid consumption, the new combined leaching process reduces the nickel and cobalt leaching rates by 3.74% and 4.62% respectively, and the concentration of liquid iron after leaching increases by 2.46% compared with the traditional one-stage normal pressure leaching process. g/L, but the leaching temperature is reduced by 100°C and the leaching pressure is reduced by 4.05MPa. The new process greatly reduces the leaching temperature and pressure at the expense of a small nickel-cobalt leaching rate, reduces production and operation costs and reduces equipment investment.

Example 2

Take 800g of mixed laterite nickel ore (Ni1.52%, Fe16.32%, MgO23.49%, Si16.09%), and pass through 1mm sieve to obtain -1mm under-sieve ore (Ni1.54%, Fe18.68% , MgO21.05%, Si15.19%) 512g, +1mm sieve ore (Ni1.47%, Fe11.95%, MgO28.03%, Si17.76%) 288g, add water to adjust the slurry concentration to 35%, using The 98% H ₂ SO ₄ solution is leached with autothermal stirring under normal pressure, the leaching temperature is 100°C, and after 5 hours of leaching, the nickel leaching rate reaches 98.45%, and the total acid consumption is 512g, which is 1t acid/t ore.

Take 288g+1mm sieve ore and grind it, add water to adjust the slurry concentration to 35%, mix it with the slurry after one-stage -1mm under-sieve ore leaching under normal pressure, then put it into the autoclave for two-stage pressure leaching, at a leaching temperature of 160°C Under leaching for 1.5h, the leaching pressure is 0.48MPa, the total nickel leaching rate reaches 94.05%, and the total acid consumption is 640kg/t ore. The Fe content of the solution after leaching was 2.47g/L.

Compared with traditional crafts:

(1) One-stage atmospheric pressure leaching process

Take 800g of mixed lateritic nickel ore (Ni1.52%, Fe16.32%, MgO23.49%, Si16.09%) with the same quality and composition, add water after grinding to adjust the slurry concentration to 35%, and use 98% _H2 The SO ₄ solution is leached with self-heating and stirring under normal pressure, the leaching temperature is 100°C, and after 5 hours of leaching, the nickel leaching rate is 81.64%, the acid consumption is 512g, and the total acid is 640kg/t ore. The Fe content of the solution after leaching was 34.27g/L.

Compared with the traditional atmospheric pressure leaching process, under the same acid consumption conditions, the nickel leaching rate of the new combined leaching process is 12.41% higher than that of the traditional one-stage atmospheric pressure leaching process, and the concentration of liquid iron after leaching is reduced by 31.80g/L. The burden of the subsequent iron removal process is reduced.

(2) One stage pressure leaching process

Take 800g of mixed lateritic nickel ore (Ni1.52%, Fe16.32%, MgO23.49%, Si16.09%) with the same quality and composition, add water after grinding to adjust the slurry concentration to 35%, and use 98% _H2 SO ₄ is leached under pressure in an autoclave with a leaching temperature of 250°C and a leaching pressure of 4.5MPa. After 1 hour of leaching, the nickel leaching rate reaches 98.83%, and the acid consumption is 512g, resulting in 640kg acid/t ore. The Fe content of the solution after leaching was 1.03g/L.

Compared with the traditional pressure leaching process, under the same acid consumption conditions, the nickel leaching rate of the new combined leaching process is 4.78% lower than that of the traditional one-stage atmospheric pressure leaching process, and the concentration of liquid iron after leaching increases by 1.44g/L, but the leaching temperature The leaching pressure is lowered by 90°C and 4.02MPa. The new process greatly reduces the leaching temperature and pressure at the expense of a smaller nickel leaching rate, reduces production and operation costs and reduces equipment investment.

Example 3

420.5kg (dry basis) limonite-type lateritic nickel ore (Ni1.18%, Co0.10%, Fe41.15%, MgO2.45%) was crushed and ground, and 98% H ₂ SO ₄ solution was used in the normal Self-heating and stirring leaching was performed under pressure. After 4 hours of leaching, the leaching rates of nickel and cobalt reached 97.55% and 95.37%, respectively, and the total acid consumption was 462.55kg, which was 1.1t acid/t ore.

Take 420.5kg (dry basis) of serpentine-type lateritic nickel ore (Ni1.55%, Co0.07%, Fe5.43%, MgO28.95%), adjust the slurry concentration to 33%-35%, and normal pressure After leaching, the ore slurry is mixed and sent to a pressure kettle for two-stage pressure leaching. Stirring and leaching under normal pressure for 2 hours at a leaching temperature of 140-160 ° C, the leaching rates of nickel and cobalt reach 94.14% and 92.58% respectively, and the obtained pressure leaching The pulp is 1298.33kg.

After pressure leaching, the slurry is added to limestone slurry, and a mixed gas of SO ₂ and air is introduced to neutralize and remove impurities at 90-100°C. The reaction time is 3-4 hours, and the pH value at the end point is controlled to be 3-4. After removing impurities, the liquid Fe< 0.1g/L, Al<0.1g/L, Mn<0.12g/L, Ni, Co loss rate<1.5%.

After removing impurities, the pulp is filtered and washed to obtain 1862.62L of Ni4.05g/L solution, and 50-100g/L NaOH solution is added to carry out nickel-cobalt precipitation at 40-60°C. The reaction time is 2-3h, and the precipitation rate of Ni and Co >99.5%, 19.13kg (dry basis) of nickel-cobalt enrichment was obtained, and the contents of Ni and Co in the enrichment were 39.23% and 2.85%, respectively.

After precipitation, the liquid is neutralized with lime slurry, so that most of the metal ions in the solution are precipitated to meet environmental protection discharge requirements.

Example 4

2248.7kg (dry basis) of mixed laterite nickel ore was screened at 1mm to obtain -1mm fine-grained ore 1506.6 (Ni1.52%, Co0.072%, Fe20.86%, Mg11.75%), +1mm coarse Grain size ore 741.2kg (Ni1.46%, Co0.043%, Fe9.06%, Mg18.19%), -1mm fine-grained ore in five 30L continuous leaching stirring tanks using 98% H ₂ SO ₄ Autothermal leaching was carried out under pressure, the leaching cycle was 5 hours, the leaching temperature was 95-105°C, the initial pulp concentration was 33%, and the atmospheric pressure leaching was carried out continuously for 210 hours, and a total of 1506.6kg of ore was processed, and the nickel and cobalt leaching rates reached 98.46% and 96.37% respectively. , a total of 1506.5kg acid consumption, 1.0t acid/t ore.

+1mm coarse-grained ore is crushed and ground and then mixed with the slurry after atmospheric leaching and continuously sent to a 68L horizontal 5-compartment autoclave through a diaphragm pump for secondary leaching. The reaction temperature is 150°C, the pressure is 4.5atm, and the leaching cycle is 2h. , The pressure leaching was carried out continuously for 210 hours, and a total of 741.2kg of coarse-grained ore was processed, and the total leaching rates of nickel and cobalt reached 94.33% and 92.17%, respectively.

Example 5

1135.9kg (dry basis) of mixed lateritic nickel ore was screened at 1mm to obtain -1mm fine-grained ore 728.1 (Ni1.30%, Co0.062%, Fe21.92%, Mg12.75%), +1mm coarse Grain size ore 408.1kg (Ni1.27%, Co0.047%, Fe10.26%, Mg19.01%), -1mm fine-grained ore in five 30L continuous leaching stirring tanks using 98% H ₂ SO ₄ Autothermal leaching was carried out under pressure, the leaching period was 4 hours, the leaching temperature was 90-110°C, the initial pulp concentration was 33%, and the atmospheric pressure leaching was carried out continuously for 90 hours, a total of 728.1kg of ore was processed, and the leaching rates of nickel and cobalt reached 98.59% and 96.05% respectively , a total of 728.3kg acid consumption, 1.0t acid/t ore.

+1mm coarse-grained ore is crushed and ground and leached at normal pressure. The slurry is continuously sent to a 68L horizontal 5-compartment through a diaphragm pump, mixed and sent to a pressurized kettle for two-stage leaching. The reaction temperature is 150°C and the pressure is 4.5atm. The period is 90 minutes, and the pressure leaching is carried out continuously for 90 hours. A total of 408.1 kg of coarse-grained ore is processed, and the total leaching rates of nickel and cobalt reach 94.19% and 92.25%, respectively.

The invention provides a method for extracting nickel and cobalt from laterite nickel ore, in particular to a method for extracting intermediate products of nickel and cobalt concentrates from different types of laterite nickel ore. Its characteristic is that the laterite nickel ore is processed by the process of "atmospheric pressure stirring leaching - low temperature pressure leaching - leaching pulp neutralization and impurity removal - nickel and cobalt precipitation", and finally produces nickel and cobalt enrichment.

The present invention is compared with the pyrotechnics and wet processes in the prior art: the limonite-type laterite nickel ore is crushed and graded, and concentrated sulfuric acid is added to carry out a section of normal pressure stirring and self-heating leaching, and the serpentine-type laterite nickel ore is crushed and milled The pulp after the mine and the first stage of leaching are sent to the autoclave at the same time, and the serpentine is leached out by the acid produced by the residual acid of the first stage of normal pressure leaching and the iron precipitation in the autoclave.

According to the different raw materials, the same mixed laterite nickel ore can also be processed, that is, after the mixed laterite nickel ore is classified, the fine-grained ore is added with concentrated sulfuric acid for a period of normal pressure stirring and leaching, and the ore on the screen is crushed and ground. After the first stage of leaching, the pulp is sent to the autoclave at the same time, and the coarse-grained ore is leached by using the residual acid of the first stage of normal pressure leaching and the acid generated by the iron precipitation in the autoclave.

Therefore, the present invention has no special requirements on ore type and grade, and has wide adaptability of raw materials. Compared with traditional atmospheric pressure leaching, it can greatly increase the leaching rate of valuable metals, reduce sulfuric acid consumption and the impurity content in pulp after leaching, and compared with traditional pressure leaching Compared with the method, the reaction temperature and pressure of the pressurized leaching section can be greatly reduced, and the investment, energy consumption and production cost can be reduced.

The invention adopts the normal pressure-pressurization combined leaching method, and the process is simple and the cost is saved.

In addition, the recovery rates of Ni and Co in the whole process of the present invention are respectively >90% and >88%, which are higher than the treatment methods in the existing non-high pressure acid leaching technology.

Claims (10)

1. a new technology of laterite nickel ore joint leaching, is characterized in that: comprise the following steps: (1) One-stage atmospheric pressure leaching: Limonite-type laterite nickel ore is crushed, ore-ground, and concentrated sulfuric acid is added, and self-heating leaching is carried out under atmospheric pressure stirring; (2) Two-stage pressure leaching: the pulp after one stage leaching is added into serpentine pulp, and the second stage leaching is carried out in an autoclave (preferably, the leaching temperature and pressure can be lower than the traditional pressure leaching process of laterite nickel ore ); (3) Neutralization of the pulp after leaching: add limestone slurry to the pulp after leaching, and pass in a mixed gas or add an oxidant to neutralize and remove impurities; (4) Cobalt-nickel precipitation: After the leached pulp is densely washed, NaOH is added to neutralize the precipitation to obtain nickel-cobalt enrichment. 2. The process as claimed in claim 1, characterized in that: the serpentine-type laterite nickel ore is sent into the autoclave simultaneously with the pulp after the first stage of leaching after crushing and grinding, and the residual acid is leached out by the first stage of atmospheric pressure. And the acid leaching serpentine generated by iron precipitation in the autoclave. 3. The process as claimed in claims 1 and 2, characterized in that: the mixed laterite-nickel ore is classified in the first section of normal-pressure stirring leaching, and concentrated sulfuric acid is added to the fine-grained ore. 4. The process according to any one of claims 1 to 3, characterized in that: it also includes at least one of the following technical features: The dosage of concentrated sulfuric acid is 0.5-1.5t/t ore, the leaching period is 1-8h, the leaching temperature is 70-120℃, and the initial pulp concentration is 20-50%; When grading the mixed laterite nickel ore, the grading particle size is selected to be 0.1-2mm; The ratio of the amount of ore added in the second stage of pressure leaching to the amount of ore in the first stage of normal pressure leaching is 1:0.25～1:4; The two-stage pressurized leaching controls the leaching period to 1-8 hours, the leaching temperature is 120-180°C, and the leaching pressure is 3-8 atm; and In the step of neutralizing the leached ore pulp and removing impurities, the reaction temperature is 40-100° C., the reaction time is 1-6 hours, and the final pH of the solution is controlled to 2-6. 5. The process according to any one of claims 1 to 4, characterized in that: the mixed gas in the leached pulp and in the impurity removal step is air- _SO mixed gas, and the oxidant is hydrogen peroxide; and/or, The cobalt-nickel precipitation step is to remove impurities from the leached ore pulp and enter the CCD for countercurrent dense washing. The supernatant is neutralized and precipitated with NaOH solution to obtain nickel-cobalt enrichment. 6. A combined leaching system for laterite nickel ore, characterized in that, Limonite-type laterite-nickel ore primary atmospheric pressure leaching tank and serpentine slurry transition tank are connected in parallel with the mixing tank, the mixing tank, the second-stage pressure leaching tank, and the pulp neutralization tank after leaching are connected in sequence; The first stage of atmospheric pressure leaching tank is equipped with limonite-type lateritic nickel ore inlet and concentrated sulfuric acid inlet; Serpentine slurry transition tank is provided with serpentine slurry inlet and water inlet; The second-stage pressurized leaching tank is connected with the ventilation source; The slurry neutralization tank is connected with the tailings pond through the underflow thickener; The slurry neutralization tank is also communicated with the cobalt-nickel precipitation tank through the supernatant liquid pool; The cobalt-nickel precipitation tank communicates with the tail liquid treatment device through the tail liquid thickener, and communicates with the nickel-cobalt enrichment container through the filter press. 7. system as claimed in claim 6 is characterized in that: at the upstream of one section of normal pressure leaching tank of limonite type laterite nickel ore, be provided with crusher, ball mill, particle screening machine, particle thickener and/or brown Iron ore type laterite nickel ore transition tank. 8. The system according to claim 6, characterized in that: a section of slurry transition tank is arranged between a section of limonite type lateritic nickel ore normal pressure leaching tank and mixing tank; and/or A diaphragm pressurized pump is arranged between the mixing tank and the second-stage pressurized leaching tank. 9. The system according to claim 6, characterized in that: a flash tank, a defoaming tank and a second-stage leached pulp storage tank are arranged between the second-stage pressurized leaching tank and the leached pulp neutralization tank; and/ or After leaching, the slurry neutralization tank is equipped with a neutralizer inlet and a secondary leaching slurry inlet. 10. The system according to claim 6, characterized in that: the underflow thickener is provided with a flocculant inlet and a washing water inlet; and/or The cobalt-nickel precipitation tank is provided with a supernatant liquid inlet and a precipitant inlet.

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