AU2008237569A1

AU2008237569A1 - A process for concentration of nickel and joint production of iron red from nickel laterite

Info

Publication number: AU2008237569A1
Application number: AU2008237569A
Authority: AU
Inventors: Xingxiang Fan; Xiaowei Guan; Yaqin Guo; Baiyu Li; Weifeng Tong; Yunhua Wang; Xiaofeng Wu; Yuedong Wu; Linhan Zan; Jiachun Zhao
Original assignee: Sino Platinum Metals Co Ltd
Current assignee: Sino Platinum Metals Co Ltd
Priority date: 2008-02-02
Filing date: 2008-10-29
Publication date: 2009-08-20
Anticipated expiration: 2028-10-29
Also published as: AU2008237569B2; CN101230422A; AU2008237569B8; AU2008237569A8

Description

S&F Ref: 881549 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address Sino-Platinum Metals Co. Ltd., of No. 988, Keji Road, of Applicant: The High and New Technology Industry Development Zone, Kunming, Yunnan, 650106, China Actual Inventor(s): Yunhua Wang Xingxiang Fan Xiaowei Guan Baiyu Li Xiaofeng Wu Jiachun Zhao Yuedong Wu Yaqin Guo Linhan Zan Weifeng Tong Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: A process for concentration of nickel and joint production of iron red from nickel laterite The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(1825235_1) A process for concentration of nickel and joint production of iron red from nickel laterite Technical Field The present invention relates to the field of non-ferrous metal metallurgy, particularly to a 5 process for treating nickel laterite by pyro- and hydro-metallurgy combining technology. Background Art It is well known that the exploiting processes of nickel laterite are roughly divided into three kinds of pyrometallurgical, hydrometallurgical and pyro- and hydrometallurgical processes. 10 Pyrometallurgical process mainly consists in producing granular nickel, smelting ferronickel and smelting nickel matte. Hydrometallurgical process mainly consists in pressure acid leaching. Pyro- and hydro-metallurgical process mainly consists in reduction roasting- atmospheric ammonia leaching and segregation-reduction roasting-mineral dressing. Mo Shuchi, et al. disclosed, in "Investigation on Charge Grade Ferronickel Production IS Through Selective Reduction Of Low Grade Nickel Oxide Mineral", Non-Ferrous Metal (Smelting Section), No. 1, 1994, a process using laterite containing low nickel as raw material. The low nickel mineral used in the experiments had a chemical composition of (by %): SiO 2 7.31, A1 2 0 3 6.11, TFe 4.77, CaO 3.29, MnO 0.44, NiO 0.91, FeO 0.72, P 0.44. The charge grade ferronickel containing Ni 2.85-5.02%, Crs1.05%, C 0.013%-5.28%, P 0.034%-0.098% was produced by 20 selective reduction process. The problem of the process is: since the nickel grade was low, electric furnace smelting was used, energy consumption was high, and correspondingly production cost was high. If the nickel grade was greater than 1.2, and the production cost was lower when adopting this process. Liu Daxing reported, in "Recent Development in Nickel and Cobalt Recovery Technologies 25 from Laterite", Non-Ferrous Metal (Smelting Section), No. 3, 2002, different treating processes might be used for different types of nickel laterites. Pyrometallurgical process is usually used for treating Garnierite. The pyrometallurgical process for treating nickel laterite comprises two smelting processes. One of the smelting processes is reducing smelting in blast furnaces or electric furnaces to give ferronickel. Higher temperature was reached by using electric furnace 30 smelting, and the atmosphere in the furnace can be easily controlled. The charge should be pre-dried. The drying and preheating were usually carried out in rotary kilns. During electric furnace reducing smelting, almost all oxides of nickel and cobalt were reduced into metals, while iron needed not to be completely reduced into metal iron. The reduction extent of iron was regulated via the addition of coke as reducing agent. The components of the resultant ferronickel 35 were (%): Ni+Co 25-45; C 0.02-0.06; S 0.02-0.05; Si 0.02-1.5; P 0.01-0.03; Fe 55-75. In addition, 2 the garnierite could be sulfidizing smelted by adding sulfidizers to yield nickel matte. Gypsum was most commonly used sulfidizer. Matte making smelting was usually carried out in a blast furnace, or in an electric furnace. The composition of nickel matte was regulated by addition of a reducing agent (powder coke) and a sulfidizer (gypsum). The resultant low nickel matte (generally 5 containing Ni+Co=20%-30%) was transferred to rotary kilns to convert into high nickel matte. He Huanhua described, in 'Review on Nickel Oxide Ore Treating Processes", Chinese Non-Ferrous Metallurgy, No. 6, 2004, the smelter that use pyro- and hydrometallurgical combining processes for treating nickel oxides. At present, only Oyama Smelter of Nippon Yakim has adopted this process in the world. The process comprises: crude ore was finely ground and 10 blended with powder coal, pelleted (whether adding segregation chlorinating agent or not should be further verified), the pellets was dried and subjected to high temperature reduction roasting, the roasted ore was finely ground, slurried, and subjected to mineral dressing (gravity separation and magnetic separation) to yield ferronickel product. The remarkable feature of this process was its low production cost, 85% energy consumption was provided by coal (per ton of ore consumed 1s 160-180 kg coal). As compared with electric furnace smelting (80% energy consumption was electric energy, per ton of ore consumed 560-600 kW-h electric energy), the energy consumption of the former was only about 30% of the latter. The main problems of the process were the effective blending of powder coal and ores, and the stable control of the temperature of reduction roasting. These problems frequently make technical indexes unstable. However, from the viewpoint of low 20 production cost and suitable for treating low grade nickel oxide minerals, the process was worth being further perfected and extented. Li Zhicai has applied a patent of atmosphere leaching process for treating low iron nickel oxide ores (Chinese Application No. 200610046808.9). An atmosphere leaching process for treating low iron nickel oxide ores comprises: wet grinding nickel oxide ores to a particle sizes0.8 25 mm; then liquid-solid separating, the water content of the filter slag being required to be 20%-35%; adding concentrated sulfuric acid to the filter slag in an amount of 70-90% of the amount of the dried ore; after acid hydrolysis and drying, storing the mineral for 1-5 days; leaching to precipitate iron at a charging speed <5 g/L min, liquid-solid ratio of 2-4, leach solution temperature of 90-100CC for 2-3 hours; the addition amount of neutralizer was 10-14% of the amount of the dried ore, the pH 30 of the leach solution was controlled at 2.5-3.5; liquid-solid separating by conventional process to yield leach solution and precipitated iron slag. Cao Guohua applied a patent of a process for extraction of nickel and cobalt by heap leaching of low grade nickel laterite (Chinese Application No.200510010915.1). The invention provides a process for extraction of nickel and cobalt by heap leaching of low grade nickel laterite, 35 comprising: crushing the ore to control average particle size of the ore less than 2 cm; adding ores 3 of 100 mesh-1.5cm directly to a heap, and meanwhile mixing the ores of particle size of less than 100 mesh and the ores of particle size of greater than 1.5cm at a mass ratio of 0.5-0.8:1 and adding into the heap; spraying and drip spraying with a spray solution at 5-18% acidity and 15-30 L/m 2 .h spraying intensity; collecting the sprayed and drip sprayed leach solution and formulating to 5 allow the concentration of nickel ion in the leach solution up to 2-4 g/L to give a leach solution containing nickel and cobalt. Canadian Faen-Habaxi introduced the leaching of nickel laterite at high temperature and pressure using sulfuric acid, see "Latest Development on Pressure Leaching Process", Foreign Metal Mineral Dressing, No. 19, 1998. Although Fe20 3 containing a great amount of laterite was 1o dissolved in sulfuric acid, trivalent iron ion was hydrated at high temperature to precipitate iron oxides and producing acids. Nickel from Kuban laterite located in Moa was recovered by using a vertical autoclave lined with acid-resisting bricks at 2500C and 4,000 kPa. Pressure acid leaching of nickel laterite has the advantages of high leaching efficiency and short leaching duration, and has the disadvantages of large equipment investment, high requirements of equipments, high acid 15 consumption for ores with high magnesium content, and high cost when low grade nickel laterite was treated. Therefore, pressure acid leaching has high requirements to raw materials. Acid leaching processes were suitable for treating nickel oxide ores with low magnesium content. Too high magnesium content in the ores would increase acid consumption, enhance operation cost, and also take influences on the technological process. 20 Japanese E.C Sanchezi et al. disclosed, in "Improving the Leaching efficiency of Mg and Ni by Chemical Activation Treatment of Garnierite", Foreign Beneficiation Express, No. 9, 1998, grinding garnierite containing quartz, magnetite and other impurities in a planetary gear ball mill, and leaching the ground ore in 0.5 mol/L HCI at 297K. The ore was dry milled to make the structure of garnierite transform from crystalline to non-crystalline, while SiO 2 and magnetite 25 remained crystalline unchanged. Such dynamic activated garnierite leaded to high leaching efficiency of magnesium and nickel in HCI solution. About 80% Mg and Ni were extracted, and only about 20% Si was extracted. Milling ores for a short time could effectively extract Mg and Ni from ores, and thereby depressing the extraction of Si. The researches on the exploiting technologies of nickel laterite have been quite active in the 30 world. Sulfuric acid atmospheric leaching processes are suitable for treating nickel oxide ores having low content of magnesium oxide and high content of limonite. Too high content of magnesium oxide in ores will increase acid consumption and enhance production cost, at a result, a great amount of magnesium sulfate and a small amount of ferrous sulfate are produced, bringing about difficulty to the subsequent treatments, meanwhile polluting environments, and causing 35 influences to technological process. High pressure acid leaching process can treat >1.2% grade 4 of limonite and sapropel. Generally, Mg is lower than 5%, the recovery of nickel and cobalt is greater than 90%. The consumption of sulfuric acid is the main consumption cost. It is necessary to maintain residual acid to ensure leaching efficiency. At the same time, the investment of equipments is large, and the maintenance cost is also high. Only electric 5 consumption of fire electric furnace smelting nickel laterite is about 50% of the cost of the operation, in addition of the fuel consumption in drying of nickel oxide ores before smelting, and roasting pretreatment process, the energy consumption cost may account for greater than 65% of the operation cost, hence, a large amount of electric energy is consumed; in addition, the ratio of silicon to magnesia in the raw materials is required, the energy consumption is high, and the investment is 1o large. Reduction roasting-ammonia leaching process can be used for treating <1.5% grade nickel laterite with a high magnesium content, the process has a smelting recovery of 85%, low recovery of cobalt, and high energy consumption. As compared with traditional wet leaching processes, the present invention can provide a process for enrichment of nickel from nickel laterite and joint producing iron red, said process has 1s the advantages of broad source of raw materials, high production efficiency, high nickel recovery, low cost and high utilization of resources, and so on. Summary of the Invention The object of the invention is to provide a new technique for concentration of nickel, said 20 technique comprising reducing carbon-containing nickel laterite pellet in rotary hearth furnace, magnetic separation to obtain primary ferronickel powder, pressure oxidizing leaching the primary ferronickel powder, and precipitating nickel with sodium hydroxide. The present invention has the advantages of broad sources of raw materials, high production efficiency, high recovery of nickel, low production cost, high utility of resources and so on. During the reducing of present technique, 25 90% energy consumption is provided by coal, without consuming expensive electric energy, and primary ferronickel powder can be obtained by grinding separation. Besides, during the pressure oxidizing leaching, the iron and the nickel in the primary ferronickel powder can be converted into iron red and nickel sulfate, respectively, by controlling the amount of acid, and nickel and iron can be effectively separated by filtration. 30 The present invention is achieved by the following steps: crushing nickel laterite until -200 mesh particles occupy 60-80%, adding carboneous reducing agent in an amount of 2-8% of the weight of the crude ore, adding an additive of calces in an amount of 3-10% of the weight of the crude ore, blending and grinding, pelleting into 15-20 mm pellet by means of ball forming machine, drying at 200-4000C for 4-6 hours, and rapid reducing in converter at 1000-14000C for 15-40 min. 35 After reduction roasting, the roasted product is coarse crushed, and then wet ball milled at an ore 5 pulp concentration of 40-70% for 30-90 min. After ball milling, the ground ore is separated by means of magnetic separator at 1000-3000 Gauss to obtain the primary ferronickel powder with >4% nickel content. The ferronickel powder is pressure oxidizing leached under following conditions: the ratio of liquid to solid is 3:1 to 8:1, the amount of acid is 25-50% of the weight of the s primary ferronickel powder, the leaching temperature is 120-1800C, the leaching pressure is 1.0-1.8 Mpa, and the leaching duration is 120-180 min. Upon the completion of the oxidizing leaching, the resultant is filtrated and washed to give iron red and nickel sulfate solution, respectively. The nickel sulfate is subjected nickel precipitation using sodium hydroxide to give nickel hydroxide. The economic technical indexes achieved under these conditions are as follows: the nickel io hydroxide product contains up to 30-40% nickel, the direct recovery of nickel reaches 70-75%, the iron red contains 62-68% iron, and the recovery of iron is 70-75%. As compared with traditional wet leaching processes, the present invention can provide a process for enrichment of nickel from nickel laterite and joint producing iron red, said process has the advantages of broad source of raw materials, high production efficiency, high nickel recovery, is low cost and high utilization of resources and so on. According to the present invention, the primary ferronickel powder is obtained only by adding a reducing agent and an additive and subjecting to blending and grinding, pelleting, drying, roasting, magnetic separation. The primary ferronickel is subjected to pressure oxidizing leaching, filtration and washing to obtain iron red and nickel sulfate solution. Finally, the nickel hydroxide is obtained by precipitating nickel with sodium 20 hydroxide. Therefore, the concentration of nickel is achieved. The present invention has no requirements to the composition of nickel laterite raw materials. All nickel laterites can be treated by using the process of the invention and the concentration of nickel and joint production of iron red can be fulfilled, regardless of high magnesium content, high iron content or high silicon content as well as high or low grade of nickel. The economic technical indexes achieved under these 25 conditions are as follows: the nickel hydroxide product contains up to 30-40% nickel, the direct recovery of nickel reaches 70-75%, the iron red contains 62-68% iron, and the recovery of iron is 70-75%. Therefore, the present invention provides a new process for treating different types of nickel laterites and has important application and extension prospects. 30 Description of the Drawings Fig. 1 is the flow chart of the process of present invention. Preferred Embodiments of the Invention 6 Example 1 1. The chemical components of magnesium nickel laterite raw materials were: Ni 0.84-1.10%, Mg 19.25-23.92%, Fe 9.47-11.01%, Co 0.024-0.028%, Al 0.050-0.070%, Si 15.04-20.78%. 5 2. Technological conditions: 5,000g nickel laterite was crushed and ground until -200 mesh particles occupy 70%, added carboneous raw materials in an amount of 5% of the weight of the crude ore and additive of calces in an amount of 7% of the weight of the crude ore, blended and ground, pelleted into 15-20 mm pellets by means of ball forming machine, dried at 2500C for 4 hours, rapid reduced in a rotary hearth furnace at 1,3000C for 30 min. After the reduction, the 1o resultant was coarse crushed, and then wet ball milled at an ore pulp concentration of 60% for 30 min. After ball milling, the ground ore was separated by means of magnetic separator at 2,000 Gauss to obtain the primary ferronickel powder with 4.5% nickel content. The ferronickel powder was pressure oxidizing leached under following conditions: liquid to solid ratio was 3:1, the amount of acid was 40% of the weight of the primary ferronickel powder, the leaching temperature was is 1600C, the leaching pressure is 1.5 MPa, and the leaching duration was 160 min. Upon the completion of the oxidizing leaching, the resultant was filtrated and washed to give iron red and nickel sulfate solution, respectively. The nickel sulfate was subjected nickel precipitation using sodium hydroxide to give nickel hydroxide. The economic technical indexes achieved under these conditions were: the content of nickel in the nickel hydroxide product was up to 35.81%, the 20 direct recovery of nickel reached 72.81%, the content of iron in the iron red was 65.02%, and the recovery of iron was 72.16%. Example 2 1. The chemical components of iron nickel laterite raw materials were: Ni 1.11-1.23%, Mg 25 8.04-10.12%, Fe 22.14-25.99%, Co 0.070-0.081%, Al 4.07-4.88%, Si 10.44-13.37%. 2. Technological conditions: 8,000g nickel laterite was crushed and ground until -200 mesh particles occupy 65%, added carboneous raw materials in an amount of 3% of the weight of the crude ore and additive of calces in an amount of 5% of the weight of the crude ore, blended and ground, pelleted into 15-20 mm pellets by means of ball forming machine, dried at 2500C for 4 30 hours, rapid reduced in a rotary hearth furnace at 13800C for 20 min. After the reduction, the resultant was coarse crushed, and then wet ball milled at an ore pulp concentration of 70% for 60 min. After ball milling, the ground ore was separated by means of magnetic separator at 1,500 Gauss to obtain the primary ferronickel powder with 4.72% nickel content. The ferronickel powder was pressure oxidizing leached under following conditions: liquid to solid ratio was 4:1, the amount 35 of acid was 30% of the weight of the primary ferronickel powder, the leaching temperature was 7 1700C, the leaching pressure was 1.8 MPa, and the leaching duration was 180 min. Upon the completion of the oxidizing leaching, the resultant was filtrated and washed to give iron red and nickel sulfate solution, respectively. The nickel sulfate was subjected nickel precipitation using sodium hydroxide to give nickel hydroxide. The economic technical indexes achieved under 5 these conditions were: the content of nickel in the nickel hydroxide product was up to 32.47%, the direct recovery of nickel reached 70.08%, the content of iron in the iron red was 66.89%, and the recovery of iron was 75.32%. Example 3 10 1. Magnesium nickel laterite and iron nickel laterite were blended as raw materials, their chemical compositions were: Ni 1.02-1.22%, Mg 12.02-16.01%, Fe 7.06-9.55%, Co 0.048-0.067%, Al 2.070-3.18%, Si 14.37-18.48%. 2. Technological conditions: 20,000g nickel laterite was crushed and ground until -200 mesh particles occupy 72%, added carboneous raw materials in an amount of 4% of the weight of is the crude ore and additive of calces in an amount of 6% of the weight of the crude ore, blended and ground, pelleted into 15-20 mm pellets by means of ball forming machine, dried at 2500C for 4 hours, rapid reduced in a rotary hearth furnace at 1,3600C for 40 min. After the reduction, the resultant was coarse crushed, and then wet ball milled at an ore pulp concentration of 50% for 90 min. After ball milling, the ground ore was separated by means of magnetic separator at 2500 20 Gauss to obtain the primary ferronickel powder with 4.67% nickel content. The ferronickel powder was pressure oxidizing leached under following conditions: liquid to solid ratio was 4:1, the amount of acid was 35% of the weight of the primary ferronickel powder, the leaching temperature was 1500C, the leaching pressure was 1.7 MPa, and the leaching duration was 120 min. Upon the completion of the oxidizing leaching, the resultant was filtrated and washed to give iron red and 25 nickel sulfate solution, respectively. The nickel sulfate was subjected nickel precipitation using sodium hydroxide to give nickel hydroxide. The economic technical indexes achieved under these conditions were: the content of nickel in the nickel hydroxide product was up to 36.94%, the direct recovery of nickel reached 73.71%, the content of iron in the iron red was 64.01%, and the recovery of iron was 77.70%. 30

Claims

1. A process for concentration of nickel and joint production of iron red from nickel laterite, wherein the process comprises the following steps: crushing and grinding nickel laterite, adding carboneous raw materials and additives, blending and grinding, pelleting into pellets in ball forming 5 machine, drying, rapid reducing in rotary hearth furnace, after reduction roasting, coarse crushing, wet milling, separating at 1000-3000 Gauss by means of magnetic separator to give primary ferronickel powder having >4% nickel content, pressure oxidizing leaching the primary ferronickel powder, upon the completion of oxidizing leaching, filtering and washing to obtain iron red and nickel sulfate solution, precipitating nickel with sodium hydroxide to obtain nickel hydroxide. 10

2. The process for concentration of nickel and joint production of iron red from nickel laterite according to claim 1, wherein the additive is calces.

3. The process for concentration of nickel and joint production of iron red from nickel laterite according to claim 1 or 2, wherein the reduction in the rotary hearth furnace is carried out at

1000-14000C for 15-40 min. is

4. The process for concentration of nickel and joint production of iron red from nickel laterite according to any one of claims 1 to 3, wherein the ore pulp concentration during wet ball milling is 40-70%, and the ball milling duration is 30-90 min.

5. The process for concentration of nickel and joint production of iron red from nickel laterite according to any one of claims 1 to 4, wherein the nickel laterite is crushed and ground until 20 -200 mesh particles occupy 60-80%.

6. The process for concentration of nickel and joint production of iron red from nickel laterite according to any one of claims 1 to 5, wherein the carboneous raw material is present in amount of 2-8% of the weight of the crude ore.

7. The process for concentration of nickel and joint production of iron red from nickel 25 laterite according to any one of claims 1 to 6, wherein the composite additive is present in amount of 3-10% of the weight of the crude ore.

8. The process for concentration of nickel and joint production of iron red from nickel laterite according to any one of claims 1 to 7, wherein the pellets have a size of 15-20 mm.

9. The process for concentration of nickel and joint production of iron red from nickel 30 laterite according to any one of claims 1 to 8, wherein the drying is carried out at 200-4000C for 4-6 hours.

10. The process for concentration of nickel and joint production of iron red from nickel laterite according to any one of claims 1 to 9, wherein the pressure oxidizing leaching of the primary ferronickel powder is carried out under following conditions: liquid to solid ratio is 3:1-8:1, the 9 amount of acid is 25-50% of the weight of the primary ferronickel powder, the leaching temperature is 120-1800C, the leaching pressure is 1.0-1.8 MPa, and the leaching duration is 120-180min.

11. A process for concentration of nickel and joint production of iron red from nickel laterite, said process substantially as hereinbefore described with reference to any one of the examples. s

12. Iron red prepared by the process of any one of claims 1 to 11. Dated 27 October, 2008 Sino-Platinum Metals Co. Ltd. Patent Attorneys for the Applicant/Nominated Person 10 SPRUSON & FERGUSON