A composite precipitant for hydrometallurgical extraction of laterite nickel ore and a method for hydrometallurgical extraction of laterite nickel ore

Abstract

The application discloses a composite precipitant for wet refining of laterite nickel ore and a wet refining method of laterite nickel ore. The composite precipitant for wet refining of laterite nickel ore is composed of a mixture of magnesium oxide and sodium hydroxide, and the mass fraction of sodium hydroxide in the composite precipitant is greater than 0 and less than or equal to 99%. The wet refining method of laterite nickel ore comprises the following steps: directly or after being grinded, the composite precipitant is added into an acidic solution to be refined, and stirring is performed to make the composite precipitant fully react with the acidic solution to be refined; after concentration, a clear liquid and a solid-containing slurry are obtained; the solid-containing slurry is filtered and washed with water to obtain a solid containing nickel hydroxide, cobalt hydroxide or nickel hydroxide-cobalt hydroxide, so that nickel, cobalt or nickel-cobalt is precipitated. The composite precipitant and the wet refining method of laterite nickel ore have the advantages of simple process, low cost, easy process control, easy settlement and filtration of nickel hydroxide (and cobalt hydroxide) precipitation, and the production efficiency can be significantly improved and the energy consumption can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy. Specifically, it is a kind of composite precipitant for laterite nickel ore hydrometallurgy and a method for laterite nickel ore hydrometallurgy. BACKGROUND

[0002] In recent years, with the rapid increase in demand for power batteries in the new energy industry, the demand for nickel has also increased rapidly. The hydrometallurgy of laterite nickel ore has become the main process for preparing nickel at present. In a high-temperature and high-pressure environment, sulfuric acid selectively leaches Ni, Co, Mg, Mn, etc. from laterite nickel ore. After neutralization, washing, and impurity removal, a precipitant is added to produce an intermediate product MHP.

[0003] Currently, the precipitant used in the nickel-cobalt precipitation process is mainly sodium hydroxide. Although the process of precipitating nickel and cobalt with sodium hydroxide is simple, it has some drawbacks: first, the consumption of sodium hydroxide is large (4 tons of 50% liquid alkali are needed for every ton of metallic nickel), the storage area is extremely large, and the cost is high; second, sodium hydroxide is highly alkaline, resulting in very fine or viscous precipitates. This kind of precipitate is difficult to settle and filter, which is not conducive to the solid-liquid separation process, so a flocculating agent is usually used in the concentration process, increasing the operating cost; third, due to the small particle size of the precipitate, the filter cake is also difficult to wash, and the filter cake has a high water content, making it difficult to transport and process; fourth, sodium hydroxide is highly alkaline, requiring all transportation, storage containers, and process equipment to have strong alkali corrosion resistance, significantly increasing the investment cost; fifth, the treatment cost of the generated sodium sulfate solution tail water is high, and it is difficult to treat.

[0004] Using calcium oxide or calcium hydroxide as a precipitant can reduce the cost of the precipitant, but it will lead to the formation of insoluble calcium sulfate precipitate, which will remain in the nickel (cobalt) hydroxide product, not only polluting the nickel / cobalt product, but also causing the adhesion and blockage of the production process pipeline due to the stickiness of calcium sulfate, making the production process unable to run smoothly.

[0005] Therefore, it is imperative to develop a new type of precipitant with cost advantage and high production process operation efficiency. SUMMARY

[0006] To this end, the technical problem to be solved by the present application is to provide a composite precipitant for laterite nickel ore hydrometallurgy and a method for laterite nickel ore hydrometallurgy, which has easy-to-settle and filter precipitates and low filter cake water content.

[0007] To solve the above technical problems, the present application provides the following technical solutions:

[0008] A composite precipitant for laterite nickel ore hydrometallurgy is composed of a mixture of magnesium oxide and sodium hydroxide. The mass fraction of sodium hydroxide in the composite precipitant is greater than 0 and less than or equal to 99%.

[0009] The composite precipitant for wet extraction of laterite nickel ore has a mass fraction of sodium hydroxide greater than 0 and less than or equal to 40%.

[0010] The composite precipitant for wet extraction of laterite nickel ore has a mass fraction of magnesium oxide w (MgO) ≥ 88 wt.%, a loss ≤ 5 wt.%, a citric acid activity of 10-100 s, an iodine absorption value of 60-150 mg I2 / g MgO, a proportion of active magnesium oxide in the magnesium oxide of 70-95 wt.%, and a particle size D90 ≤ 100 μm;

[0011] The method for preparing the magnesium oxide comprises the following steps: crushing magnesite to a particle size of 30-80 mm, and calcining in a rotary kiln at 900-1100 °C at a kiln rotation speed of 0.5 rmp / min-2 rmp / min.

[0012] The composite precipitant for wet extraction of laterite nickel ore has a mass fraction of magnesium oxide w (MgO) ≥ 90-95 wt.%, a loss ≤ 3 wt.%, a citric acid activity of 15-40 s, an iodine absorption value of 80-130 mg I2 / g MgO, a proportion of active magnesium oxide of 80-90 wt.%, and a particle size D90 ≤ 45 μm.

[0013] The composite precipitant for wet extraction of laterite nickel ore is prepared by adding the magnesium oxide and sodium hydroxide together into a polypropylene stirring tank, stirring and mixing uniformly to obtain the composite precipitant.

[0014] The composite precipitant for wet extraction of laterite nickel ore is prepared by first dissolving sodium hydroxide in water to prepare a sodium hydroxide saturated solution, then adding magnesium oxide into the sodium hydroxide saturated solution, evaporating under stirring to obtain sodium hydroxide-adsorbed magnesium oxide, and then immersing the sodium hydroxide-adsorbed magnesium oxide in a polyvinyl alcohol solution and drying to obtain the composite precipitant.

[0015] The composite precipitant for wet extraction of laterite nickel ore has a volume ratio of the polyvinyl alcohol solution to the sodium hydroxide-adsorbed magnesium oxide of 0.5-1:1, and a concentration of the polyvinyl alcohol solution of 5 wt.%.

[0016] The method for wet extraction of laterite nickel ore comprises the following steps:

[0017] (1) adding the composite precipitant directly or after being grinded into a slurry into an acid solution to be extracted, wherein the acid solution to be extracted is an acid aqueous solution containing nickel, an acid aqueous solution containing cobalt, or an acid aqueous solution containing nickel and cobalt, and the composite precipitant is the composite precipitant described above;

[0018] (2) stirring to allow the composite precipitant to fully react with the acid solution to be extracted;

[0019] (3) The mixed solution after reaction is concentrated to obtain clear liquid and solid-containing slurry;

[0020] (4) The solid-containing slurry is filtered and washed with water to obtain a solid containing nickel hydroxide, cobalt hydroxide, or nickel hydroxide-cobalt hydroxide, thereby realizing the precipitation of nickel, cobalt or nickel-cobalt.

[0021] In step (1) of the above-mentioned laterite nickel ore wet refining method, the pH of the acidic solution to be refined is 3-6, preferably 4.5-5.5.

[0022] In step (1) of the above-mentioned laterite nickel ore wet refining method, the total amount of sodium hydroxide and magnesium oxide in the composite precipitant is 0.7-1.2 times, preferably 0.8-1.0 times, the total amount of nickel and cobalt in the acidic solution to be refined.

[0023] In step (1) of the above-mentioned laterite nickel ore wet refining method, the slurry concentration of the composite precipitant is greater than 0 wt.% and less than or equal to 50 wt.%, preferably 5%-20%; the slurry is stirred by mechanical stirring at a stirring rate of 50-300 r / min, preferably 100-150 r / min; the slurry time is 5-200 min, preferably 8-30 min.

[0024] In step (2) of the above-mentioned laterite nickel ore wet refining method, the composite precipitant reacts with the acidic solution to be refined at a temperature of 25-95℃, preferably 50-65℃.

[0025] In step (2) of the above-mentioned laterite nickel ore wet refining method, the reaction time of the composite precipitant with the acidic solution to be refined is 3-8 h, preferably 4-6 h.

[0026] In step (2) of the above-mentioned laterite nickel ore wet refining method, the composite precipitant reacts with the acidic solution to be refined by magnetic stirring or mechanical stirring at a stirring rate of 200-600 r / min.

[0027] In step (2) of the above-mentioned laterite nickel ore wet refining method, the pH at the end of the reaction of the composite precipitant with the acidic solution to be refined is controlled at 7-9, preferably 7.5-8.2.

[0028] In step (3) of the above-mentioned laterite nickel ore wet refining method, the concentration of the mixed solution after reaction is natural sedimentation or adding 0.01-0.15 wt.% of PAM for sedimentation.

[0029] The chemical reactions involved in the present application are mainly as follows:

[0030] The composite precipitant is added directly or after slurry to the solution, and the magnesium oxide hydrolysis reaction is as follows:

[0031] MgO + H2O → Mg(OH)2↓

[0032] The composite precipitant is ionized in aqueous solution:

[0033] Mg(OH)2→ Mg 2+ +2OH -

[0034] NaOH→ Na + +OH -

[0035] The composite precipitant is added to the nickel (cobalt) containing acidic solution, and the OH - ions ionized from magnesium hydroxide and sodium hydroxide combine with the nickel (cobalt) ions in the solution to form nickel hydroxide (cobalt hydroxide) precipitate:

[0036] Mg(OH)2+ NiSO4→ Ni(OH)2↓+ MgSO4

[0037] 2NaOH+ NiSO4→ Ni(OH)2↓+ Na2SO4

[0038] The technical scheme of the present application achieves the following beneficial technical effects:

[0039] (1) The composite precipitant composed of magnesium oxide and sodium hydroxide in the present application has the OH - ions ionized from unit mole of magnesium oxide being 2 times of the OH - ions ionized from sodium hydroxide, so that the single consumption of the composite precipitant is lower when producing nickel hydroxide (cobalt hydroxide) precipitate, and the cost of the precipitant is also lower.

[0040] (2) The alkalinity of the composite precipitant in the present application is relatively “milder” than the commonly used sodium hydroxide, and the local “over-alkaline” phenomenon is not easy to occur during use, the generated nickel hydroxide (cobalt hydroxide) precipitate is easy to settle, and it is also easy to filter, and the moisture content of the filter cake is lower, effectively solving the problem that it is difficult to settle and filter when using sodium hydroxide as a precipitant at present, and reducing the amount of flocculant used when the precipitate settles, reducing the cost while improving the production efficiency, and reducing the energy consumption of filter cake drying.

[0041] (3) The composite precipitant is added to the nickel (and cobalt) containing solution in the method for wet refining of laterite nickel ore in the present application, and the nickel content in the obtained nickel hydroxide (cobalt hydroxide) precipitate is above 40%, and the magnesium content is ≤2%. The composite precipitant has high efficiency in precipitating nickel (and cobalt), and the nickel content in the precipitate is relatively high.

[0042] (4) The composite precipitant and the method for wet refining of laterite nickel ore in the present application have simple process, low cost, easy process control, easy settlement and filtration of nickel hydroxide (and cobalt hydroxide) precipitate, and can significantly improve the production efficiency and reduce the energy consumption.

[0043] (5)The present application controls the particle size of magnesite entering the rotary kiln, the kiln temperature and the kiln rotation speed, so that magnesium oxide with good activity is obtained, and then the good activity magnesium oxide is compounded with sodium hydroxide to obtain a composite precipitator, which can reduce the moisture content of the filter cake of the laterite nickel ore after aluminum and iron removal, accelerate the settling rate and filtration rate, and reduce the unit consumption of the composite precipitator. The content of the good activity magnesium oxide increases the settling rate and filtration rate with the increase of the content of the magnesium oxide, and the moisture content of the filter cake decreases. At the same time, the presence of a small amount of sodium hydroxide in the composite precipitator also improves the reaction rate.

[0044] (6)According to the 0.8-1.0 times of the total amount of nickel and cobalt in the solution in the beaker, the total amount of sodium hydroxide and magnesium oxide in the composite precipitator is calculated: there is a lot of Mn 2+ in the solution to be refined. In order to prevent manganese from precipitating, the amount of precipitator added is controlled in production, so that the nickel and cobalt precipitation rate is controlled at about 80%. Although sufficient precipitator can make nickel and cobalt precipitate completely, a large amount of manganese appears in the precipitation, which reduces the proportion of nickel and cobalt in the precipitation, which is not conducive to production. Although the solution containing nickel and cobalt is an acidic solution, neutralizing the acidic solution does indeed consume a certain amount of composite precipitator, but the amount is very small and can be ignored. DETAILED DESCRIPTION

[0045] Example 1

[0046] PN-MH007 magnesium oxide and sodium hydroxide are selected to form a composite precipitator, wherein the purity of sodium hydroxide is 98%, and the performance test of PN-MH007 magnesium oxide is shown in Table 1.

[0047] Table 1 Performance index of PN-MH007 magnesium oxide

[0048]

[0049]

[0050] PN-MH007 magnesium oxide and sodium hydroxide are loaded into a polypropylene stirring tank at a mass ratio of 8:2. The stirring tank inlet and outlet are fixed with dry agents made of quicklime to prevent the composite precipitator from absorbing moisture. After the composite precipitator is uniformly mixed in the stirring tank, it is taken out and sealed for standby use.

[0051] The preparation method of PN-MH007 magnesium oxide is as follows: the magnesite is crushed to 30-60 mm, calcined in a rotary kiln at 900-1000℃, and the kiln rotation speed is 0.5-1 rmp / min.

[0052] According to the main element composition of the solution after aluminum and iron removal from the laterite nickel ore, the solution is prepared by adjusting the pH of the solution with sulfuric acid. The chemical composition of the nickel (cobalt) containing acidic solution is shown in Table 2.

[0053] Table 2 Main element composition of solution prepared according to the red soil nickel ore after aluminum removal unit: g / L

[0054] Element Ni Co Mn Mg Ca Fe 2+ ]]> Si pH Content 2.20 0.30 2.56 10.02 0.40 0.15 0.01 4.9

[0055] A certain amount of prepared acidic solution containing nickel and cobalt was taken in a beaker, placed in a constant temperature water bath, the temperature was set to 55°C, and the mechanical stirrer was turned on, the stirring rate was 350 r / min, and the solution in the beaker was stirred.

[0056] The total amount of sodium hydroxide and magnesium oxide in the composite precipitant was calculated according to 0.8 times the total amount of nickel and cobalt in the solution in the beaker, the composite precipitant was added with water, and the slurry was prepared at a concentration of 10 wt.%, mechanical stirring was used during the slurry preparation, the stirring speed was 120 r / min, and the slurry preparation process was completed after 8 min of stirring.

[0057] The composite precipitant slurry was slowly poured into the beaker containing the solution containing nickel and cobalt, and the reaction was carried out for 5 h. The pH of the solution in the beaker at the reaction endpoint was 7.7. After the reaction was completed, the beaker was quickly removed and allowed to stand, and the settling of the solids was observed. After settling (either naturally or with the addition of 0.01-0.15 wt.% PAM), the supernatant was removed, and the solid-containing slurry after concentration was vacuum filtered. After filtration, the filter cake was washed by spraying water to remove the soluble salts entrained in the filter cake. The water content of the filter cake was calculated by weighing the filter cake before and after drying, and the chemical composition of the dried filter cake was determined.

[0058] As shown in Table 3, the nickel precipitation rate in this embodiment reached 78.63%, the cobalt precipitation rate reached 80.00%, the Ni content in the nickel hydroxide precipitate reached 43.23%, the Mg content was 0.75%, the settling rate was 0.09 cm / s, and the filtration rate reached 5.55 m 3 / (m 2 ×h), the settling rate and filtration rate were much higher than those of sodium hydroxide under the same conditions, the filtration rate was good, the unit consumption of the composite precipitant was 737 kg / t (Ni+Co) , which was much lower than the unit consumption of sodium hydroxide, and the filter cake had a low water content.

[0059] Table 3 Comparison of the effects of different precipitants

[0060]

[0061] Note: 0.8 times the composite precipitant means that the total amount of sodium hydroxide and magnesium oxide in the composite precipitant is 0.8 times the total amount of nickel and cobalt in the solution, and 0.8 times the sodium hydroxide means that the amount of sodium hydroxide is 0.8 times the total amount of nickel and cobalt in the solution.

[0062] Example 2

[0063] The PN-MH007C magnesium oxide is selected as a composite precipitator with sodium hydroxide, wherein the purity of the sodium hydroxide is 98%, and the performance of the PN-MH007C magnesium oxide is shown in Table 4.

[0064] Table 4 Performance index of PN-MH007C magnesium oxide

[0065]

[0066]

[0067] The PN-MH007C magnesium oxide and sodium hydroxide are loaded into a polypropylene stirring tank at a mass ratio of 1:1, the feeding port and discharging port of the stirring tank are fixedly placed with dry agents made of quicklime to prevent the composite precipitator from absorbing moisture, and the composite precipitator is taken out after being uniformly mixed in the stirring tank and is sealed for standby.

[0068] The preparation method of the PN-MH007C magnesium oxide is as follows: the magnesite is crushed to 40-70 mm, and is calcined at 950-1050°C in a rotary kiln at a rotation speed of 1-1.5 rmp / min.

[0069] The solution is prepared according to the main element composition of the solution after removing aluminum and iron from the laterite nickel ore, and the pH of the solution is adjusted by sulfuric acid, and the chemical composition of the nickel (cobalt) containing acid solution is shown in Table 5.

[0070] Table 5 Preparation of solution according to main element composition of solution after removing aluminum from laterite nickel ore Unit: g / L

[0071] Element Ni Co Mn Mg Ca Fe 2+ ]] Si pH Content 2.20 0.30 2.56 10.02 0.40 0.15 0.01 5.1

[0072] A certain amount of prepared nickel and cobalt containing acid solution is taken in a beaker, placed in a constant temperature water bath, the temperature is set to 65°C, and a mechanical stirrer is turned on, the stirring rate is 500 r / min, and the solution in the beaker is stirred.

[0073] The total amount of substance of sodium hydroxide and magnesium oxide in the composite precipitator is calculated according to 0.85 times the total amount of substance of nickel and cobalt in the solution in the beaker, the composite precipitator is added with water, and the slurry is prepared at a concentration of 20 wt.%, mechanical stirring is adopted during the slurry preparation, the rotation speed is 150 r / min, and the stirring time is 25 min, and the slurry preparation process is completed.

[0074] The slurry of the composite precipitator is slowly poured into the beaker containing the nickel (and cobalt) solution, and the reaction is allowed to proceed for 6 hours. The pH of the solution in the beaker at the end of the reaction is 7.8. After the reaction is completed, the beaker is quickly removed and allowed to stand, and the settling of the solid is observed. After settling (either naturally or with the addition of 0.01-0.15 wt.% PAM), the supernatant is removed, and the slurry containing the solid after concentration is vacuum filtered. After filtration, the surface of the filter cake is sprayed with water to wash the filter cake of soluble salts. The moisture content of the filter cake is calculated by weighing the filter cake before and after drying, and the chemical composition of the dried filter cake is determined.

[0075] As shown in Table 6, the nickel precipitation rate reached 84.09%, the cobalt precipitation rate reached 83.33%, the Ni content in the nickel hydroxide precipitate reached 46.33%, the Mg content was 0.37%, the settling rate was 0.07 cm / s, and the filtration rate reached 2.29 m 3 / (m 2 h), the settling rate and filtration rate were much higher than those of sodium hydroxide under the same conditions, the filtration rate was good, the unit consumption of the composite precipitator was 930 kg / t (Ni+Co) , the unit consumption was much lower than that of sodium hydroxide, and the moisture content of the filter cake was also lower.

[0076] Table 6 Comparison of the effects of different precipitators

[0077]

[0078] Example 3

[0079] The PN-MH007D magnesium oxide and sodium hydroxide are selected to form a composite precipitator, and the purity of the sodium hydroxide is 98%. The performance of the PN-MH007D magnesium oxide is shown in Table 7.

[0080] Table 7 Performance indicators of PN-MH007 magnesium oxide

[0081]

[0082]

[0083] The PN-MH007D magnesium oxide and sodium hydroxide are loaded into a polypropylene stirring tank at a mass ratio of 2:8. The feeding port and discharging port of the stirring tank are fixed with dry agents made of quicklime to prevent the composite precipitator from absorbing moisture. After the composite precipitator is uniformly mixed in the stirring tank, it is taken out and sealed for use.

[0084] The preparation method of the PN-MH007D magnesium oxide is as follows: the magnesite is crushed to 50-80 mm and calcined in a rotary kiln at 1000-1100°C, and the rotation speed of the kiln is 1.5-2 rpm / min.

[0085] The solution was prepared according to the main element composition of the solution after removing aluminum and iron from the laterite nickel ore, and the pH of the solution was adjusted by sulfuric acid. The chemical composition of the acidic solution containing nickel (cobalt) is shown in Table 8.

[0086] Table 8: Solution prepared according to the main element composition of the solution after removing aluminum from the laterite nickel ore

[0087] Element Ni Co Mn Mg Ca Fe 2+ ]]> Si pH Content 2.20 0.30 2.56 10.02 0.40 0.15 0.01 5.2

[0088] A certain amount of prepared acidic solution containing nickel and cobalt was taken in a beaker, placed in a constant temperature water bath, the temperature was set to 50°C, and the mechanical stirrer was turned on, the stirring rate was 450 r / min, and the solution in the beaker was stirred.

[0089] The total amount of sodium hydroxide and magnesium oxide in the composite precipitant was calculated according to 0.95 times the total amount of nickel and cobalt in the solution in the beaker. The composite precipitant was added to water and slurried at a concentration of 15 wt.%. Mechanical stirring was used during slurry preparation, the stirring speed was 130 r / min, and the slurry was stirred for 20 min to complete the slurry preparation process.

[0090] The composite precipitant slurry was slowly poured into the beaker containing the solution containing nickel and cobalt, and the reaction was carried out for 6 h. The pH of the solution in the beaker at the end of the reaction was 7.9. After the reaction was completed, the beaker was quickly removed and allowed to stand. The settling of the solids was observed. After settling (either naturally or with the addition of 0.01-0.15 wt.% PAM), the supernatant was removed, and the solid-containing slurry after concentration was vacuum filtered. After filtration, the filter cake was washed by spraying water to remove the soluble salts entrained in the filter cake. The moisture content of the filter cake was calculated by weighing the filter cake before and after drying, and the chemical composition of the dried filter cake was determined.

[0091] As shown in Table 9, the nickel precipitation rate in this embodiment reached 84.54%, the cobalt precipitation rate reached 76.67%, the Ni content in the nickel hydroxide precipitate was 40.65%, the Mg content was 0.43%, the settling rate was 0.03 cm / s, and the filtration rate reached 0.81 m 3 / (m 2 h), the settling rate and filtration rate were much higher than those of sodium hydroxide under the same conditions, the filtration rate was good, the unit consumption of the composite precipitant was 1220 kg / t (Ni+Co) , the unit consumption was lower than that of sodium hydroxide, and the moisture content of the filter cake was also lower.

[0092] Table 9: Comparison of the effects of different precipitants

[0093]

[0094] Example 4

[0095] PN-MH007 magnesium oxide and sodium hydroxide were selected as the composite precipitator, the purity of sodium hydroxide was 98%, and the performance of PN-MH007 magnesium oxide was shown in Table 10.

[0096] Table 10 Performance index of PN-MH007 magnesium oxide

[0097]

[0098]

[0099] The difference between this example and Example 1 was that the method of preparing the composite precipitator was different (the mass ratio of magnesium oxide to sodium hydroxide was still 8:2): sodium hydroxide was dissolved in water to prepare a saturated sodium hydroxide solution, then magnesium oxide was added to the saturated sodium hydroxide solution, and was evaporated under stirring to obtain magnesium oxide adsorbed with sodium hydroxide. The magnesium oxide adsorbed with sodium hydroxide was impregnated with a polyvinyl alcohol solution with a volume ratio of 1:1, and was dried, the concentration of the polyvinyl alcohol solution used was 5wt.%, to obtain a magnesium oxide-sodium hydroxide composite precipitator.

[0100] A solution was prepared according to the main element composition of the solution after removing aluminum and iron from the laterite nickel ore, and the pH of the solution was adjusted by sulfuric acid. The chemical composition of the nickel (cobalt) containing acidic solution was shown in Table 11.

[0101] Table 11 Preparation of solution according to the main element composition of the solution after removing aluminum from the laterite nickel ore Unit: g / L

[0102] Element Ni Co Mn Mg Ca Fe 2+ ]] Si pH Content 2.20 0.30 2.56 10.02 0.40 0.15 0.01 4.9

[0103] A certain amount of prepared nickel and cobalt containing acidic solution was taken in a beaker, placed in a constant temperature water bath, the temperature was set to 55℃, and the mechanical stirrer was turned on, the stirring rate was 350r / min, and the solution in the beaker was stirred.

[0104] According to 0.8 times of the total amount of nickel and cobalt in the solution in the beaker, the total amount of sodium hydroxide and magnesium oxide in the composite precipitator was calculated, the composite precipitator was added with water, and the concentration was adjusted to 10wt.%, mechanical stirring was used during the slurry preparation process, the stirring rate was 120r / min, and the stirring time was 8min.

[0105] The composite precipitator slurry was slowly poured into the beaker containing the nickel and cobalt containing solution, and the reaction was carried out for 5h. The pH of the solution in the beaker at the reaction endpoint was 7.6. After the reaction was completed, the beaker was quickly taken out, and the solid settlement was observed. After settling (natural settling or adding 0.01-0.15wt.% PAM for settling), the supernatant was taken out, the solid-containing slurry after concentration was vacuum filtered, and the filter cake surface was sprayed with water to wash the soluble salts entrained in the filter cake. The weight of the filter cake before and after drying was measured to calculate the water content of the filter cake, and the chemical composition of the filter cake after drying was detected.

[0106] As shown in Table 12, the nickel precipitation rate in this embodiment reached 78.18%, the cobalt precipitation rate reached 76.67%, in the nickel hydroxide precipitation, the Ni content reached 43.18%, the Mg content was 0.72%, the settling rate was 0.101 cm / s, the filtration rate reached 6.28 m 3 / (m 2 ×h), the settling rate and the filtration rate were much higher than those of sodium hydroxide under the same conditions, the filtration rate was good, the single consumption of the composite precipitator was 741 kg / t (Ni+Co) , the single consumption was much lower than that of sodium hydroxide, and the moisture content of the filter cake was also lower.

[0107] Table 12 Comparison of the use effects of precipitators

[0108]

[0109] Sodium hydroxide adsorbs polyvinyl alcohol and causes polyvinyl alcohol to crystallize, thereby sealing sodium hydroxide in the micropores of magnesium oxide particles, so that the magnesium oxide-sodium hydroxide composite precipitator can slowly release sodium hydroxide in the reaction, increase the particle size of the precipitate, improve the settling and filtration speed, and reduce the moisture content of the filter cake.

[0110] Obviously, the above embodiments are merely examples for the sake of clarity, and are not limiting of the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary or possible to exhaust all embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the claims of the present patent application.

Claims

1. A composite precipitant for wet refining of laterite nickel ore, characterized in that, A mixture of magnesium oxide and sodium hydroxide, wherein the mass fraction of sodium hydroxide in the composite precipitant is greater than 0 and less than or equal to 40%; In magnesium oxide w (MgO) ≥88wt.%, loss on ignition ≤5wt.%, citric acid activity value is 10-100s, iodine uptake value is 60-150mgI2 / gMgO, active magnesium oxide content in magnesium oxide is 70-95wt.%, particle size D90≤100μm; First, sodium hydroxide is dissolved in water to prepare a saturated sodium hydroxide solution. Then, magnesium oxide is added to the saturated sodium hydroxide solution and evaporated to dryness while stirring to obtain magnesium oxide that has adsorbed sodium hydroxide. After impregnating the magnesium oxide that has adsorbed sodium hydroxide with a polyvinyl alcohol solution and drying, a composite precipitant is obtained.

2. The composite precipitant for wet refining of laterite nickel ore according to claim 1, characterized in that, Preparation method of magnesium oxide: crush magnesite to a particle size of 30-80 mm, and calcine it in a rotary kiln at 900-1100℃ with a kiln speed of 0.5 rpm to 2 rpm.

3. The composite precipitant for wet refining of laterite nickel ore according to claim 1, characterized in that, In magnesium oxide w (MgO) The MgO content is 90–95 wt.%, with a loss ≤ 3 wt.%, citric acid activity of 15–40 s, iodine uptake value of 80–130 mg I2 / g MgO, active magnesium oxide content of 80–90 wt.%, and particle size D90 ≤ 45 μm.

4. The composite precipitant for wet refining of laterite nickel ore according to claim 1, characterized in that, The volume ratio of polyvinyl alcohol solution to magnesium oxide adsorbing sodium hydroxide is 0.5–1:1, and the concentration of polyvinyl alcohol solution is 5 wt.%.

5. A wet refining method for laterite nickel ore, characterized in that, Includes the following steps: (1) The composite precipitant is added directly or after slurry preparation to the acidic solution to be refined, wherein the acidic solution to be refined is a nickel-containing acidic aqueous solution, a cobalt-containing acidic aqueous solution, or a nickel-cobalt-containing acidic aqueous solution; the composite precipitant is the composite precipitant according to any one of claims 1 to 4; (2) Stirring to ensure that the composite precipitant reacts fully with the acidic solution to be refined; (3) The mixed solution after the reaction is concentrated to obtain a clear liquid and a slurry containing solids; (4) The slurry containing solids is filtered and washed with water to obtain a solid containing nickel hydroxide, cobalt hydroxide, or nickel hydroxide-cobalt hydroxide, thereby achieving the precipitation of nickel, cobalt or nickel-cobalt.

6. The wet refining method for laterite nickel ore according to claim 5, characterized in that, In step (1): the pH of the acidic solution to be refined is 3 to 6.

7. The wet refining method for laterite nickel ore according to claim 6, characterized in that, The pH of the acidic solution to be refined is 4.5–5.

5.

8. The wet refining method for laterite nickel ore according to claim 5, characterized in that, In step (1): the total amount of sodium hydroxide and magnesium oxide in the composite precipitant is 0.7 to 1.2 times the total amount of nickel and cobalt in the acidic solution to be refined; in step (1): the concentration of the composite precipitant in the slurry is greater than 0 wt.% and less than or equal to 50 wt.%; the slurry is prepared by mechanical stirring at a speed of 50 to 300 r / min; the slurry preparation time is 5 to 200 min; in step (2): the composite precipitant reacts with the acidic solution to be refined at a temperature of 25 to 95℃; In step (2): the reaction time between the composite precipitant and the acidic solution to be refined is 3 to 8 hours; in step (2): the reaction between the composite precipitant and the acidic solution to be refined is carried out by magnetic stirring or mechanical stirring at a stirring rate of 200 to 600 r / min; in step (2): the pH of the reaction endpoint between the composite precipitant and the acidic solution to be refined is controlled at 7 to 9; in step (3): the concentration of the mixed solution after the reaction is carried out by natural sedimentation or by adding 0.01 to 0.15 wt.% PAM for sedimentation.

9. The wet refining method for laterite nickel ore according to claim 8, characterized in that, In step (1): the total amount of sodium hydroxide and magnesium oxide in the composite precipitant is 0.8 to 1.0 times the total amount of nickel and cobalt in the acidic solution to be refined; in step (1): the concentration of the composite precipitant is 5% to 20%; the slurry is prepared by mechanical stirring at a speed of 100 to 150 r / min; the preparation time is 8 to 30 min; in step (2): the composite precipitant reacts with the acidic solution to be refined at a temperature of 50 to 65℃; in step (2): the reaction time of the composite precipitant with the acidic solution to be refined is 4 to 6 h; in step (2): the final pH of the reaction between the composite precipitant and the acidic solution to be refined is controlled at 7.5 to 8.2.

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