Patent Description:
Laterite ore is nickel oxide ore formed by metamorphosing nickel-containing peridotite in tropical or subtropical areas through large-scale, long-term weathering and eluviation. Due to differences in geographic locations, climatic conditions, and weathering degrees, types of laterite ore around the world are not completely the same. In a weathering process, layered deposits are generally produced, and the complete or most thorough weathering products near the crust, as the depth increases, becomes less weathering products gradually, and finally, at a deeper place, becomes unweathered rocks. In a highly weathered layer, usually, most of contained nickel is finely distributed in finely divided goethite particles, and the highly weathered layer is usually referred to as limonite generally containing a high proportion of iron and a low proportion of silicon and magnesium. Nickel contained in a lightly weathered layer is generally more likely to be contained in various magnesium silicate minerals such as serpentine. There may be many other nickel-containing silicate minerals in a zone of incomplete weathering. A partially weathered zone having a high magnesium content is usually referred to as saprolite or garnierite which generally contains a low proportion of iron and a high proportion of silicon and magnesium. In some deposits, there is another zone that mainly contains nontronite clay and that is usually located between limonite and saprolite, which is referred to as transitional ore. "Low-grade laterite ore" refers to laterite ore without saprolite ore, that is, laterite ore consisting of limonite and transitional ore. Generally, limonite is a main component of laterite nickel ore, and accounts for <NUM>-<NUM>% of a total amount of the laterite ore, saprolite accounts for <NUM>-<NUM>%, and transitional ore accounts for <NUM>%. The difficulty in recovering nickel and cobalt from laterite nickel ore is that before chemical treatment is carried out to separate useful metal components (such as nickel and cobalt), the useful components of nickel cannot usually be fully concentrated in physical manners, that is, cannot be concentrated by using an ore dressing technology, resulting in very high costs of treatment on laterite nickel ore. In addition, due to the different minerals and chemical composition of limonite and saprolite ore, the ores are usually not suitable for being treated by using the same treatment technology. For decades, a method for lowering costs of treatment on laterite nickel ore has been looked for.

Well-known metallurgical methods for treating laterite nickel ore include a pyrometallurgical process, a hydrometallurgical process, and a pyro-hydrometallurgical process.

It is a metallurgical method in which carbonaceous material such as coke or semi-coke are reduced or sulfurated in a metallurgical furnace to produce ferronickel or nickel matte. The pyrometallurgical process includes technical solutions such as smelting ferronickel by using a rotary kiln-electric furnace (RKEF), smelting ferronickel by using a sintering machine-blast furnace, smelting ferronickel by using a ball press machine-blast furnace, smelting low nickel matte by using a spherical agglomerate-blast furnace, and smelting low nickel matte by using an RKFF.

The pyrometallurgical process is suitable for treating saprolite laterite nickel ore of a high silicon and magnesium, low iron saprolite. Only ferronickel and nickel matte can be produced through the process, and cobalt cannot be recovered, which limits application of the pyrometallurgical process. Moreover, during the pyrometallurgical process, a content of iron in ore needs to be controlled, to obtain high-grade ferronickel. Although the blast furnace can treat high iron ore, a product of low nickel pig iron with poor quality is generally obtain. A specific proportion of iron to nickel needs to be controlled to obtain high-grade ferronickel. For meeting the requirements of pyrometallurgical slagging, a ratio of silicon to magnesium of the ore also needs to be controlled within an appropriate range, and a content of aluminum oxide cannot be too high, which limits a use range of the pyrometallurgical process.

In the hydrometallurgical process, valuable metals, such as nickel and cobalt, are leached from laterite nickel ore generally by using leaching agents such as sulfuric acid and hydrochloric acid, and then, a nickel sulfate or electrolytic nickel product is obtained by using methods such as purification and electrolysis. The hydrometallurgical process is suitable for treating limonite.

The hydrometallurgical technology includes processes such as high-pressure acid leaching and reduction roasting-ammonia leaching, as well as atmospheric pressure acid leaching and heap leaching that have emerged in recent years. The heap leaching technology has a low leaching rate and is only suitable for treating laterite ore having a high magnesium content. The reduction roasting-ammonia leaching process is rarely used due to high energy consumption and a long process procedure. The atmospheric pressure acid leaching technology is simple in terms of operation, and does not require expensive autoclaves. However, in the atmospheric pressure acid leaching, a large amount of acid needs to be consumed for completely dissolving minerals, so low magnesium, low iron nickel ore is generally selected to reduce acid consumption. In addition, the atmospheric pressure acid leaching has a disadvantage that a leachate contains various metal ions, resulting in more complex subsequent leaching and separation procedures. In the high-pressure acid leaching process, laterite nickel ore is leached by using sulfuric acid at a high temperature and a high pressure. Under the high temperature and high pressure, metal minerals in the ore are almost completely dissolved. Dissolved iron is rapidly hydrolyzed into a hematite precipitate at the high temperature, and nickel, cobalt, and the like remain in the solution. After cooling, leaching residue containing iron and silicon is separated from the solution containing nickel and cobalt through a series of concentration and washing, that is, the so-called counter-current decantation washing circuit. Therefore, a main objective of the leaching process, separation of nickel and iron, is achieved. Advantages of the high-pressure acid leaching process are that leaching rates of nickel and cobalt are high, a reaction speed is high, a reaction time is short, iron does not consume sulfuric acid in the acid leaching process theoretically, and a hydrolysis product is a hematite precipitate. However, disadvantages of the high-pressure acid leaching process are also obvious, which requires complex high-temperature and high-pressure autoclaves and related equipment whose installation and maintenance are expensive. The high-pressure leaching process is limited to the treatment of raw materials, such as limonite, because saprolite ore contains a high content of magnesium that causes a large increase in consumption of sulfuric acid.

At present, the only plant that treats nickel oxide by using a pyro-hydrometallurgical process in the world is Oheyama Smelter of the Nippon Yakin Company. A main process comprises that raw ore is ground and mixed with powdered coal to form agglomerate ore, the agglomerate ore is dried and subjected to high-temperature reduction roasting, the roasted agglomerate ore is reground, and pulp is subjected to gravity separation and magnetic separation, to obtain a nickel-iron alloy product. The biggest characteristic of the process is that energy in energy consumption is provided by coal, and as a result production costs are low. However, energy consumed by electric furnace smelting in the pyrometallurgical process is provided by electric energy. There is a big price difference in terms of energy consumption costs between the two. There are still many problems in the pyro-hydrometallurgical process. Although Oheyama Smelter has been improved the process many times, technologies in the process are still not stable enough. After decades, the production scale of Oheyama Smelter has remained at about <NUM> tons of nickel per year.

Wang Yunhua et al. provided a technical solution of reduction-grinding treatment for different types of laterite nickel ore in a <CIT>). The application of Wang Yunhua et al. relates to a technology for recovering nickel from laterite nickel ore, which comprises that: the laterite nickel ore is crushed and ground; a carbonaceous reducing agent and a compound additive are added to the crushed and ground laterite nickel ore at a specific ratio and mixed with the laterite nickel ore for grinding; the grinded mixtures are formed into spherical agglomerates of <NUM>-<NUM> by using a spherical agglomerate forming machine, dried at <NUM>-<NUM> for <NUM>-<NUM> hours, and is subjected to reduction roasting in a rotary kiln whose temperature is controlled at <NUM>-<NUM>; after the reduction roasting, the roasted spherical agglomerates are subjected to coarse crushing, wet ball milling according to a specific ratio of pulp, gravity separation by using a shaking table to obtain nickel concentrates; and the obtained nickel concentrates are sorted by using a <NUM>-<NUM> gauss magnetic separator to obtain high-grade nickel-iron mixed concentrates with a nickel content of <NUM>-<NUM>%. The technical solution has the characteristics of strong raw material adaptability, a short process procedure, environmental friendliness, and using coal as a main energy source instead of using expensive electricity as an energy source, which provides a novel method for processing different types of laterite nickel ore, and has good application and promotion prospects. However, the solution has the following problems that need to be alleviated in subsequent applications: (<NUM>) Due to fluctuations of components in the laterite nickel ore, the rotary kiln has the serious ring formation problem during a roasting process. (<NUM>) Since the entire reduction process is carried out under melting conditions, nickel is distributed in silicate lattices and is relatively dispersed. The metallurgical kinetic conditions do not allow partially reduced nickel to be effectively migrated, concentrated, and recovered, and a recovery rate of nickel is extremely low. (<NUM>) The nickel grade of concentrates is limited by a content of iron content in the nickel ore. When the content of iron is high, the nickel grade is low. When the content of iron is low, the dose of iron as a trapping agent is small, and the recovery rate of nickel is low.

<CIT> discloses a mineral separation technology for nickel laterite ore. Nickel laterite ore is divided into a limonite type and a garnierite type according to different components, the limonite type nickel laterite ore is located on the upper portion of an ore deposit, and the garnierite type nickel laterite ore is located on the lower portion of the ore deposit. Mineral separation is carried out on the limonite type nickel laterite ore and the garnierite type nickel laterite ore respectively, the water content of the selected nickel laterite ore is then detected, the ore with the water content ranging from <NUM>% to <NUM>% is dry type nickel laterite ore and is processed through a pyrometallurgy technology, and the ore with the water content ranging from <NUM>% to <NUM>% is wet type nickel laterite ore and is processed through a wet metallurgy technology.

<CIT> discloses a red clay nickel ore heap leaching method. The method is characterized by comprising the following steps of: (<NUM>) crushing, washing and grading ores, filling the graded ores into a plurality of heap leaching pools; (<NUM>) adding a newly prepared ore leaching agent into the first leaching pool to perform leaching extraction on nickel of the ores in the first leaching pool, and collecting the leachate in a liquid storage pool through a liquid outlet; (<NUM>) conveying the leachate collected in the last step to the next leaching pool leaching pool to perform leaching extraction on the nickel of the ores, and collecting the leachate in a liquid storage pool through a liquid outlet; (<NUM>) repeating the step (<NUM>) until the concentration of the nickel in the leachate reaches a preset concentration, and conveying the leachate to a purification process; and (<NUM>), repeating the step (<NUM>).

<CIT> provides a laterite nickel ore treatment method, which comprises the following steps: sulfuric acid is adopted to carry out pressure leaching treatment on laterite nickel ore pulp, so that laterite nickel ore leachate is obtained; first neutralizer is added into the laterite nickel ore leachate to precipitate iron and aluminum, so that a nickel-and-cobalt-contained solution is obtained; second neutralizer is added into the nickel-and-cobalt-contained solution to precipitate nickel and cobalt, so that a crude product is obtained, and the crude product is gypseous nickel cobalt hydroxide; sulfuric acid is adopted to carry out releaching treatment on the crude product, so that a nickel cobalt sulfate solution and gypsum ore pulp are obtained; after the nickel cobalt sulfate solution is extracted, purified and evaporatively crystallized, nickel sulfate and cobalt sulfate are respectively obtained; the first neutralizer is limestone ore pulp or calcium hydroxide pulp, and the second neutralizer is calcium hydroxide pulp.

Treating laterite nickel ore by using a combined method of an RKEF and atmospheric-pressure leaching has also been put forward. However, because limonite cannot be treated with the atmospheric-pressure leaching, only low iron, low magnesium transition-layer ore can be selected, which is difficult to match. In addition, the atmospheric-pressure leaching cannot be effectively implemented due to the problems of high acid consumption, a low nickel recovery rate, a large amount of smelting wastewater that is difficult to treat, and high smelting costs.

Although nickel ore with different properties is distributed in layers, there is no obvious boundary between the layers. With the undulation of terrain, it is difficult to separate the nickel ore having a specific property from others during mining, resulting to mixing of nickel ore having different properties, which also brings a challenge to stability of the treatment process.

The features of the method according to the present invention are set out in the appended set of claims.

An objective of the present disclosure is to provide a method for producing battery-grade nickel sulfate by using laterite nickel ore, to obtain a battery-grade nickel sulfate product. In the process, advantages of technical solutions, namely, pyrometallurgy, hydrometallurgy, and heap leaching, are fully utilized, and the technical solutions are integrated together to complement each other, leading to advantages of low production costs, environmentally friendliness, high in recovery rates of nickel and cobalt, effective utilization of nickel ore resources, and broad application and promotion prospects.

To achieve the foregoing objective, the present disclosure uses the following technical solutions:
A method for producing battery-grade nickel sulfate by using laterite nickel ore is provided, including the following steps:.

In step (<NUM>), the battery-grade nickel sulfate differs from electroplating-grade nickel sulfate in that in battery-grade nickel sulfate, requirements on contents of magnetic substances, cobalt, magnesium, and silicon, are relatively high, where a content of Mg < <NUM>%, a content of Si < <NUM>%, a content of magnetic substance < <NUM>%, and a content of Co < <NUM>%.

Preferably, in step (<NUM>), the laterite nickel ore mainly includes the following components by mass percentage: <NUM>-<NUM>% of Ni, <NUM>-<NUM>% of Fe, <NUM>-<NUM>% of Mg, <NUM>-<NUM>% of Co, and <NUM>-<NUM>% of Si.

In step (<NUM>), the lump ore and the sediment ore are sorted according to a particle size, where a particle size of the lump ore is greater than <NUM>, and a particle size of the sediment ore is less than <NUM>.

Preferably, in step (<NUM>), during the crushing, the lump ore is crushed to <NUM>-<NUM>.

Preferably, in step (<NUM>), for the heap leaching, a temperature is <NUM>-<NUM>, and a time is <NUM>-<NUM> days.

Preferably, in step (<NUM>), a specific operation of the heap leaching comprises: putting the crushed lump ore into a heap leaching pool, and then leaching nickel from the ore in a manner of spraying and soaking in sulfuric acid, to obtain the crude nickel sulfate solution.

More preferably, a mass concentration of the dilute sulfuric acid is <NUM>-<NUM>%.

Preferably, in step (<NUM>), in the sorting, high chromium ore, low iron, high magnesium ore, and high iron, low magnesium ore are separated by using a gravity separation method such as a trough ore washer, a spiral chute, or a shaking table. The high chromium ore may be sold directly as a finished product.

In step (<NUM>), the high chromium ore comprises <NUM>-<NUM>% of chromium and <NUM>-<NUM>% of nickel; the low iron, high magnesium ore is mainly garnierite and comprises <NUM>-<NUM>% of nickel, <NUM>-<NUM>% of magnesium, <NUM>-<NUM>% of iron, and <NUM>-<NUM>% of silicon; and the high iron, low magnesium ore is mainly limonite and comprises <NUM>-<NUM>% of nickel, <NUM>-<NUM>% of iron, <NUM>-<NUM>% of magnesium, and <NUM>-<NUM>% of silicon. The low iron, high magnesium ore and the high iron, low magnesium ore are different in granularity and property.

Preferably, in step (<NUM>), during the drying, the low iron, high magnesium ore is dried to a water content of <NUM>-<NUM>%.

Preferably, in step (<NUM>), for the roasting, a temperature is <NUM>-<NUM>, and a time is <NUM>-<NUM>.

Preferably, in step (<NUM>), for the reducing, a temperature is <NUM>-<NUM>, and a time is <NUM>-<NUM>.

Preferably, in step (<NUM>), a reducing agent used for the reducing is at least one of coke, semi-coke, or anthracite.

By reducing an addition amount of the reducing agent, that is, the addition amount of the reducing agent is <NUM>-<NUM>% of dry ore, a nickel content of ferronickel is controlled, and as a result a grade of ferronickel reaches <NUM>-<NUM>%, thereby reducing an iron content of ferronickel and reducing costs of sulfurating and blowing.

Preferably, in step (<NUM>), for the sulfurating, a temperature is <NUM>-<NUM>, and a time is <NUM>-<NUM>.

Preferably, in step (<NUM>), a nickel content of the low nickel matte is <NUM>-<NUM>%. Relatively, nickel-sulfur-iron compounds containing more than <NUM>% nickel are referred to as high nickel matte, and nickel-sulfur-iron compounds containing less than <NUM>% of nickel are referred to as low nickel matte.

Preferably, in step (<NUM>), the pressure of the water extraction is <NUM>-<NUM> MPa.

Preferably, in step (<NUM>), for the oxygen pressure leaching, a temperature is <NUM>-<NUM>, and a pressure is <NUM>-<NUM> MPa.

Preferably, in step (<NUM>), for the pressure leaching, a temperature is <NUM>-<NUM>, and a pressure is <NUM>-<NUM> MPa.

Preferably, in step (<NUM>), an acidic extractant is used in the extraction, during which Fe<NUM>+, Mn<NUM>+, Co<NUM>+, Mg<NUM>+, and Ca<NUM>+ are extracted to obtain a nickel sulfate solution, and the acidic extractant is at least one of P204 (diisooctyl phosphate), P507 (mono2-ethylhexyl <NUM>-ethylhexyl phosphate), or C272 (di(<NUM>,<NUM>,<NUM>-trimethylpentyl)).

More preferably, in step (<NUM>), a specific operation of the extraction comprises: under conditions of a temperature of <NUM>-<NUM> and a pH value of <NUM>-<NUM>, first extracting Fe<NUM>+ and Mn<NUM>+ by using P204, and then extracting Co<NUM>+, Mg<NUM>+, and Ca<NUM>+ by using either or both of P507 (mono2-ethylhexyl <NUM>-ethylhexyl phosphate) and C272 (di(<NUM>,<NUM>,<NUM>-trimethylpentyl)), to obtain the nickel sulfate solution.

The present disclosure further provides use of the foregoing method in separation and purification of nickel ore.

At present, selection of a granularity parameter is very important during ore dressing. Performance of ore after ore dressing is further considered for the ore dressing. Otherwise, the high iron, low magnesium ore and the low iron, high magnesium ore cannot be separated. Consequently, advantages of various processes cannot be brought into play. An appropriate granularity dividing point not only requires a large quantity of experimental demonstrations, but requires that experiments are carried out again to explore parameters based on experience of inventors and improvement to processes due to different weathering degrees of ore in mines. Therefore, the granularity dividing point is not an absolute fixed value. In the present disclosure, the high iron, low magnesium ore and the low iron, high magnesium ore are first separated, and then the laterite nickel ore is treated by using the combined method of the RKEF process, the pressure leaching process, and the heap leaching process, and as a result the high iron, low magnesium ore and the low iron, high magnesium ore as well as large stone ore having a relatively low grade (generally, low-grade large stone ore is abandoned in mines) can be treated simultaneously. Different ores are treated with appropriate processes by utilizing characteristics of the ores, and as a result advantages of pyrometallurgical and hydrometallurgical processes are brought into full play and the pyrometallurgical and hydrometallurgical processes complement each other. Not only costs of treatment on ore are lowered, but also various ore resources are effectively utilized, to reduce wastewater discharge for resource saving and environmental protection.

<FIG> is a schematic diagram of a process flow of producing battery-grade nickel sulfate by using laterite nickel ore according to Example <NUM>.

To make a person skilled in the art understand the technical solutions of the present disclosure more clearly, the following examples are listed for description. It should be noted that the following examples do not limit the protection scope of the present disclosure.

Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be commercially available, or can be obtained by existing known methods.

A method for producing battery-grade nickel sulfate by using laterite nickel ore was provided, including the following steps:.

Contents of impurities in the nickel sulfate product in Example <NUM> were: cobalt (Co) = <NUM>%, iron (Fe) = <NUM>%, magnesium (Mg) = <NUM>%, manganese (Mn) = <NUM>%, and zinc (Zn) = <NUM>%. A comprehensive recovery rate of nickel ore was <NUM>% (nickel recovery rate = nickel content of product/nickel content of ore * <NUM>%), and smelting costs of nickel sulfate were <NUM> dollars/ton base nickel.

Contents of impurities in the nickel sulfate product in Example <NUM> were: cobalt (Co) = <NUM>%, iron (Fe) = <NUM>%, magnesium (Mg) = <NUM>%, manganese (Mn) = <NUM>%, and zinc (Zn) = <NUM>%. A comprehensive recovery rate of nickel ore was <NUM>%, and smelting costs of nickel sulfate were <NUM> dollars/ton base nickel.

Contents of impurities in the nickel sulfate product in Comparative example <NUM> were: cobalt (Co) = <NUM>%, iron (Fe) = <NUM>%, magnesium (Mg) = <NUM>%, manganese (Mn) = <NUM>%, and zinc (Zn) = <NUM>%. A comprehensive recovery rate of nickel ore was <NUM>%, and smelting costs of nickel sulfate were <NUM> dollars/ton base nickel.

Example <NUM> differed from Comparative Example <NUM> in that, in Comparative Example <NUM>, low iron, high magnesium ore of <NUM>-<NUM> was not separated from the sediment ore, and all the sediment ore was treated with pressure leaching. Consequently, a large amount of magnesium reacted with acid, and the acid consumption may reach <NUM> t/t-Ni. The smelting wastewater contained a large amount of Mg ions, resulting in high costs of treatment on wastewater and environmental pollution.

Example <NUM> differed from Comparative Example <NUM> in that, in Comparative Example <NUM>, high iron, low magnesium ore of <NUM>-<NUM> was not separated, and instead, all sediment ore entered an RKEF production line for producing ferronickel, resulting a high iron content of the ore and difficulty in producing high-grade ferronickel. In addition, a large amount of iron discharged from electric furnace slag (reduction) may take away part of nickel, resulting in a reduced recovery rate of nickel. During the sulfurating and blowing of the low-grade ferronickel, a large amount of iron needed to be discharged through slagging. An amount of nickel taken away by the slag was increased, and the recovery rate of nickel was reduced.

Claim 1:
A method for producing battery-grade nickel sulfate by using laterite nickel ore, comprising the following steps:
(<NUM>) obtaining lump ore and sediment ore by sorting the laterite nickel ore; wherein the lump ore and the sediment ore are sorted according to a particle size, where a particle size of the lump ore is greater than <NUM>, and a particle size of the sediment ore is less than <NUM>;
(<NUM>) obtaining a crude nickel sulfate solution A by crushing the lump ore, and then performing heap leaching;
(<NUM>) obtaining high chromium ore, low iron, high magnesium ore, and high iron, low magnesium ore by separating the sediment ore , and obtaining low nickel matte by drying, roasting, reducing, and sulfurating the low iron, high magnesium ore; wherein the high chromium ore comprises <NUM>-<NUM>% of chromium and <NUM>-<NUM>% of nickel; the low iron, high magnesium ore is mainly garnierite and comprises <NUM>-<NUM>% of nickel, <NUM>-<NUM>% of magnesium, <NUM>-<NUM>% of iron, and <NUM>-<NUM>% of silicon; and the high iron, low magnesium ore is mainly limonite and comprises <NUM>-<NUM>% of nickel, <NUM>-<NUM>% of iron, <NUM>-<NUM>% of magnesium, and <NUM>-<NUM>% of silicon;
(<NUM>) obtaining a crude nickel sulfate solution B by blowing and performing water extraction on the low nickel matte, and then performing oxygen pressure leaching;
(<NUM>) obtaining a crude nickel sulfate solution C by performing pressure leaching on the high iron, low magnesium ore; and
(<NUM>) obtaining battery-grade nickel sulfate by performing extraction on the crude nickel sulfate solution A, the crude nickel sulfate solution B, and the crude nickel sulfate solution C, and then evaporating and crystallizing; wherein, in the battery-grade nickel sulfate, a content of Mg < <NUM>%, a content of Si < <NUM>%, a content of magnetic substance < <NUM>%, and a content of Co < <NUM>%.