Preparation and application method of active magnesium oxide for cobalt precipitation

Abstract

The invention discloses a preparation and application method of active magnesium oxide for cobalt precipitation, which comprises the following steps: adding acetate during preparation of an active magnesium oxide precursor magnesium hydroxide to obtain magnesium hydroxide with a double-tooth structure; when magnesium oxide is prepared through calcination, conversion from magnesium hydroxide to magnesium oxide can be achieved at a low temperature, and meanwhile high activity is obtained; and finally, the magnesium oxide slurry is added into the cobalt precipitation pre-solution for cobalt precipitation, the cobalt precipitation effect is good, and the obtained coarse cobalt hydroxide cobalt is high in grade. The magnesium hydroxide regulating agent is used for promoting generation of magnesium oxide rich in active sites, the magnesium hydroxide regulating agent is applied to the wet metallurgy cobalt deposition process, the cobalt deposition effect of active magnesium oxide prepared through a chemical method is effectively improved, other methods except for the method for reducing the particle size and promoting the activity of magnesium oxide are developed, acetate is selected as the magnesium hydroxide regulating agent, the dosage is small, and the cost is low. Magnesium oxide obtained through calcination is high in purity, the cobalt deposition process is not affected, unit consumption of magnesium oxide can be reduced, and cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical substance preparation, and particularly to a preparation and application method of magnesium oxide for cobalt precipitation. Background Art

[0002] The metallurgical process of copper-cobalt oxide ore mostly adopts the hydrometallurgical process. Magnesium oxide is used as the main cobalt precipitant due to its advantages of high efficiency, environmental protection, economy, etc. Compared with the ore method, the magnesium oxide prepared by the chemical method has higher purity. At the same time, the ore method can only control the activity of magnesium oxide by adjusting the particle size, while the chemical method can control the size, morphology and specific surface area of the active magnesium oxide precursor by using regulators to control the activity of magnesium oxide from multiple aspects and angles. At present, in China, chemical magnesium oxide uses salt lake magnesium resources and ammonia to obtain magnesium hydroxide by coprecipitation, and then realizes the preparation of magnesium oxide for cobalt precipitation through calcination and fine grinding. The cobalt precipitation rate of this ordinary magnesium oxide for cobalt precipitation is less than 50% within 1 hour, the cobalt grade is less than 25%, and the unit consumption of magnesium oxide is greater than 1.2t / tCo. Obviously, there is a lack of an efficient magnesium oxide for cobalt precipitation at present. Summary of the Invention

[0003] Aiming at the defects existing in the prior art, the present invention provides a preparation method and application method of highly active magnesium oxide for cobalt precipitation with simple preparation process, low energy consumption, low cost, better cobalt precipitation effect and lower application unit consumption.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions: A preparation method of active magnesium oxide for cobalt precipitation is carried out according to the following steps:

[0005] 1) Weigh magnesium salt and alkali, select acetate as the regulator, and prepare bidentate magnesium hydroxide under hydrothermal conditions; by mass, magnesium salt: alkali: acetate = 11:(11 - 66):(0.5 - 3), the hydrothermal temperature is 100 - 180°C, and the time is 2 - 10h;

[0006] 2) Calcinate the bidentate magnesium hydroxide under low-energy conditions to obtain highly active magnesium oxide for cobalt precipitation, the calcination temperature is 300 - 900°C, and the calcination time is 6 - 12min.

[0007] In step 1), the acetate is ammonium acetate, sodium acetate or glacial acetic acid, and the regulator concentration is 0.02 - 2.0mol / L; the magnesium salt is magnesium chloride, magnesium nitrate or magnesium sulfate, and the concentration is 50 - 110g / L; the alkali source is ammonia water, sodium hydroxide or ammonia, n(OH － ) : n(Mg 2+ ) > 1:1.

[0008] In step 1), the hydrothermal temperature is 140 - 160°C, and the time is 2 - 6h.

[0009] In step (2), the calcination temperature is 600 - 800 °C and the calcination time is 8 min.

[0010] Based on the foregoing application method of the active magnesium oxide for cobalt precipitation, the following steps are carried out:

[0011] (1) Adjust the slurry of high - activity magnesium oxide for cobalt precipitation to a solid content of 5% - 30%. Add the slurry to the pre - cobalt - precipitation solution for cobalt precipitation at room temperature to obtain a slurry containing cobalt hydroxide. During the cobalt precipitation process, the addition amount of magnesium oxide is n(MgO):n(Co)=0.6 - 1.2:1 (molar ratio), without heating, the stirring speed is 100 - 400 r / min, and the reaction time is 10 - 60 min;

[0012] (2) Separate the solid and liquid of the slurry containing crude cobalt hydroxide obtained, and after drying, obtain a crude cobalt hydroxide product with a high cobalt grade.

[0013] In step (1), the cobalt content in the pre - cobalt - precipitation solution is 1.0 - 12.0 g / L, the manganese content is 0.3 - 3.0 g / L, the magnesium content is 0 - 3.5 g / L, the copper content is 0 - 1 g / L, and the iron ion content is 0 - 0.1 g / L.

[0014] In step (1), the addition amount of magnesium oxide is n(MgO):n(Co)=0.6 - 0.8:1, and the reaction time is 10 - 30 min.

[0015] In step (1), the solid content of magnesium oxide is 10%, and the slurry - adjusting time is 5 - 30 min, such as 10 min.

[0016] In step (2), vacuum filtration is used for solid - liquid separation, the drying temperature is 60 - 80 °C, the cobalt recovery rate is over 60%, and the cobalt grade is over 35%.

[0017] First of all, by using acetate as a regulator in the synthesis process of magnesium hydroxide, the present invention can obtain magnesium hydroxide with a bidentate coordination structure, which is beneficial to reducing the activation energy of the transformation of magnesium hydroxide to magnesium oxide and reducing the production energy consumption of magnesium oxide. Secondly, through the regulation of acetate, the bound water on the surface of magnesium hydroxide is increased, which is beneficial to the formation of rich active sites during the transformation of magnesium hydroxide to magnesium oxide. When the magnesium oxide content is the same, the activity of citric acid is increased by 72.88%. Thirdly, a small amount of CO2 volatilizes during the calcination of magnesium hydroxide to prepare magnesium oxide by the regulator, which will not enter the cobalt precipitation system, avoiding the problem of impurity ion enrichment caused by the closed - loop circulation in the cobalt precipitation system. Finally, since nickel and cobalt have similar chemical properties and are associated ores, the active magnesium oxide prepared by the present invention can also be used to recover nickel in the hydrometallurgy process. Description of the Drawings

[0018] Figure 1 It is the process flow chart of the present invention. Detailed implementation manners

[0019] The following further describes the present invention with reference to the appended Figure 1 specific embodiments:

[0020] Embodiment 1

[0021] Use MgCl₂ to prepare 80 mL of a solution containing Mg 2+ with a concentration of 100 g / L. Using ammonia water as the alkali source, n(Mg 2+ ):n(OH － ) = 1:2. Take 50 mL of analytical pure ammonia water with a content of 25%-28%. The regulator ammonium acetate is 0.4 mol / L, 20 mL. At the same time, add the MgCl₂ solution, ammonia water and ammonium acetate solution to the reaction kettle. The reaction temperature is 160 °C and the reaction time is 2 h. After the reaction, obtain the active magnesium oxide precursor sample by suction filtration, washing and drying for 5 h.

[0022] Take 5 g of the active magnesium oxide precursor sample, the calcination temperature is 600 °C, and the calcination time is 8 min to obtain the magnesium oxide product for cobalt precipitation.

[0023] Take 200 mL of the pre-cobalt precipitation solution in a glass beaker, and adjust the pH = 4.50 with a 0.01 mol / L dilute sulfuric acid solution; weigh magnesium oxide according to 0.8 times the molar amount of cobalt metal in the pre-cobalt precipitation solution, that is, 1.17 g. Use deionized water to adjust magnesium oxide into a magnesium oxide slurry with a solid content ratio (mass) of about 10%, place it in a 10 mL centrifuge tube, and mix evenly. Add the uniformly dispersed magnesium oxide slurry to the pre-cobalt precipitation solution and react at a speed of 400 r / min at room temperature for 10 min. After the reaction, perform suction filtration to obtain cobalt-containing filter residue and post-cobalt precipitation solution. The precipitated filter residue is washed with deionized water, and the washed cobalt residue is dried at 85 °C for 2 h. The cobalt content in the dried cobalt residue is detected, and the cobalt content in the filtrate is also detected.

[0024] Results: The cobalt grade in the crude cobalt hydroxide is 35.38%, the cobalt precipitation rate is 63.24%, and the single consumption of magnesium oxide is 0.86 t / t Co.

[0025] Comparative Example 1

[0026] Use MgCl₂ to prepare 80 mL of a solution containing Mg 2+ with a concentration of 100 g / L. Using ammonia water as the alkali source, n(Mg 2+ ):n(OH － ) = 1:2. Take 50 mL of analytical pure ammonia water with a content of 25%-28%. At the same time, mix the MgCl₂ solution and ammonia water. The reaction temperature is 85 °C and the reaction time is 3 h. After the reaction, obtain the active magnesium oxide precursor sample by suction filtration, washing and drying for 5 h.

[0027] The experimental conditions for the preparation of magnesium oxide and its application in cobalt precipitation are the same as those in Example 1.

[0028] Results: The cobalt grade in the crude cobalt hydroxide is 23.84%, the cobalt precipitation rate is 40.05%, and the unit consumption of magnesium oxide is 1.37 t / t Co.

[0029] Example 2

[0030] Prepare an 80 mL solution containing Mg with a concentration of 100 g / L using magnesium nitrate. Using sodium hydroxide as the alkali source, n(Mg 2+ ):n(OH 2+ ):n(OH － ) = 1:2. Take 50 mL of a sodium hydroxide solution with a concentration of 350 g / L, and 20 mL of a 0.4 mol / L sodium acetate solution as the regulator. At the same time, add the magnesium nitrate solution, sodium hydroxide solution, and sodium acetate solution to the reaction kettle. The reaction temperature is 100 °C, and the reaction time is 8 h. After the reaction, obtain the active magnesium oxide precursor sample through suction filtration, washing, and drying for 5 h.

[0031] Take 5 g of the active magnesium oxide precursor sample, calcine it at 800 °C for 8 min to obtain the magnesium oxide product for cobalt precipitation.

[0032] Take 200 mL of the solution before cobalt precipitation in a glass beaker, and adjust the pH = 4.50 with a 0.01 mol / L dilute sulfuric acid solution; weigh magnesium oxide according to 0.8 times the molar amount of cobalt metal in the solution before cobalt precipitation, that is, 1.17 g. Use deionized water to adjust the magnesium oxide into a slurry with a solid content ratio of about 10%, place it in a 10 mL centrifuge tube, and mix evenly. Add the uniformly dispersed magnesium oxide slurry to the solution before cobalt precipitation, and react at a speed of 100 r / min at room temperature for 50 min. After the reaction, perform suction filtration to obtain cobalt-containing filter residue and the solution after cobalt precipitation. Wash the precipitated filter residue with deionized water, dry the washed cobalt residue at 85 °C for 2 h, detect the cobalt content of the dried cobalt residue, and at the same time detect the cobalt content in the filtrate.

[0033] Results: The cobalt grade in the crude cobalt hydroxide is 41.59%, the cobalt precipitation rate is 73.68%, and the unit consumption of magnesium oxide is 0.87 t / t Co.

[0034] Example 3

[0035] Prepare an 80 mL solution containing Mg with a concentration of 100 g / L using magnesium sulfate. Using ammonia water as the alkali source, n(Mg 2+ ):n(OH 2+ ):n(OH －) = 1:2.5, take 50 mL of analytical pure ammonia water with a content of 25% - 28%, and 20 mL of 0.4 mol / L regulator glacial acetic acid. At the same time, add magnesium sulfate solution, ammonia water and glacial acetic acid solution to the reaction kettle. The reaction temperature is 180 °C and the reaction time is 4 h. After the reaction, filter by suction, wash and dry for 5 h to obtain the active magnesium oxide precursor sample.

[0036] Take 5 g of the active magnesium oxide precursor sample, the calcination temperature is 700 °C, and the calcination time is 8 min to obtain the magnesium oxide product for cobalt precipitation.

[0037] Take 200 mL of the solution before cobalt precipitation in a glass beaker, and adjust the pH = 4.50 with 0.01 mol / L dilute sulfuric acid solution; weigh magnesium oxide according to 0.8 times the molar amount of cobalt metal in the solution before cobalt precipitation, that is, 1.17 g. Use deionized water to adjust magnesium oxide into a magnesium oxide slurry with a solid content ratio of about 10%, place it in a 10 mL centrifuge tube, and mix evenly. Add the uniformly dispersed magnesium oxide slurry to the solution before cobalt precipitation, and react at a rotation speed of 200 r / min at room temperature for 60 min. After the reaction, filter by suction to obtain cobalt-containing filter residue and the solution after cobalt precipitation. The precipitated filter residue is washed with deionized water, and the washed cobalt residue is dried at 85 °C for 2 h. The cobalt, magnesium and manganese contents of the dried cobalt residue are detected, and the cobalt, magnesium and manganese contents in the filtrate are also detected.

[0038] Results: The cobalt grade in the crude cobalt hydroxide is 45.1%, the cobalt precipitation rate is 75.60%, and the unit consumption of magnesium oxide is 0.68 t / tCo.

[0039] Comparative Example 2

[0040] Use MgCl2 to prepare a solution with a concentration of 100 g / L and a volume of 80 mL. Use ammonia water as the alkali source, n(Mg 2+ ):n(OH 2+ ):n(OH － ) = 1:2, take 50 mL of analytical pure ammonia water with a content of 25% - 28%. At the same time, mix the MgCl2 solution and ammonia water. The reaction temperature is 85 °C and the reaction time is 3 h. After the reaction, filter by suction, wash and dry for 5 h to obtain the active magnesium oxide precursor sample. Take 5 g of the active magnesium oxide precursor sample, the calcination temperature is 800 °C, and the calcination time is 8 min to obtain the magnesium oxide product for cobalt precipitation. The experimental conditions for cobalt precipitation application are the same as those in Example 2.

[0041] Results: The cobalt grade in the crude cobalt hydroxide is 36.06%, the cobalt precipitation rate is 58.27%, and the unit consumption of magnesium oxide is 1.03 t / tCo.

[0042] From the characterization results of magnesium hydroxide with a bidentate structure, there are three differences from ordinary magnesium hydroxide: ① The (001) crystal plane of magnesium hydroxide is fully grown, much higher than the (100) and (101) crystal planes; ② The energy required for thermal decomposition is lower, and the activation energy is 114.24 kJ / mol. The activation energy of ordinary magnesium hydroxide is 127.79 kJ / mol (comparative sample), 132 kJ / mol; ③ The magnesium oxide formed after calcination has a macroporous structure, and the most probable particle size is 50 nm. The most probable particle size of the magnesium oxide formed after calcination of ordinary magnesium hydroxide is 12.65 nm.

[0043] By comparing the thermogravimetry of magnesium hydroxide products with and without acetate added, the thermal decomposition temperature of the magnesium hydroxide prepared by adding acetate is lower. Through the study of the thermal decomposition kinetics of magnesium hydroxide, the activation energy of the magnesium hydroxide regulated by acetate is calculated to be 114.24 kJ / mol, and the activation energy of the magnesium hydroxide without acetate regulation is 127.79 kJ / mol.

[0044] The surface density of magnesium atoms in the (001) crystal plane of bidentate structure magnesium hydroxide is higher than that of other crystal planes. During the crystal growth process, the (001) crystal plane is more inclined to coordinate with carboxyl groups, and the carboxyl groups form a coordination compound with the Mg atoms of magnesium hydroxide (Mg(OH) x (OCOCH3) 2-x , as follows:

[0045]

[0046] The present invention has been described in detail above. The above description is only the preferred embodiment of the present invention, and it cannot limit the scope of the present invention. That is, all equivalent changes and modifications made according to the scope of this application should still fall within the scope covered by the present invention.

Claims

1. A method for preparing active magnesium oxide for cobalt precipitation, characterized in that: Follow these steps: 1) weighing magnesium salt and alkali, selecting acetate as a regulating agent, and preparing bidentate magnesium hydroxide under hydrothermal conditions; in terms of molar amount, magnesium: alkali: acetate = 11: (11-66): (0.5-3), the hydrothermal temperature is 100-180° C., and the time is 2-10 h; 2) The bidentate magnesium hydroxide is calcined under low energy conditions to obtain high-performance active magnesium oxide for cobalt precipitation, the calcination temperature is 300-900° C., and the calcination time is 6-12 min.

2. The preparation method and application method of the active magnesium oxide for cobalt precipitation according to claim 1, characterized in that: In step 1), the acetate is ammonium acetate, sodium acetate or glacial acetic acid, and the concentration of the regulator is 0.02-2.0 mol / L; the magnesium salt is magnesium chloride, magnesium nitrate or magnesium sulfate, and the concentration is 50-110 g / L; the alkali source is ammonia water, sodium hydroxide or ammonia gas, n(OH － ):n(Mg 2+ )>1:

1.

3. The preparation method and application method of the active magnesium oxide for cobalt precipitation according to claim 1, characterized in that: In step 1), the hydrothermal temperature is 140-160° C. and the time is 2-6 h.

4. The preparation method and application method of the active magnesium oxide for cobalt precipitation according to claim 1, characterized in that: In step 2), the calcination temperature is 600-800° C. and the calcination time is 8 minutes.

5. An application method of the active magnesium oxide for cobalt precipitation according to any one of claims 1 to 4, characterized in that: Follow these steps: (1) slurrying high-activity cobalt precipitation magnesium oxide according to the solid content of 5%-30%, adding the cobalt precipitation pre-liquid to the slurry to precipitate cobalt at room temperature, and obtaining a slurry containing cobalt hydroxide; the amount of magnesium oxide added during the cobalt precipitation process is n(MgO):n(Co)=0.6-1.2:1 (molar ratio), without heating, the stirring speed is 100-400r / min, and the reaction time is 10-60min; (2) Separating the solid and liquid of the slurry containing crude cobalt hydroxide, and drying to obtain a crude cobalt hydroxide product with a high cobalt grade.

6. The application method according to claim 5, characterized in that: In step (1), the cobalt content in the cobalt precipitation pre-liquid is 1.0-12.0 g / L, the manganese content is 0.3-3.0 g / L, the magnesium content is 0-3.5 g / L, the copper content is 0-1 g / L, and the iron ion content is 0-0.1 g / L.

7. The application method according to claim 5, characterized in that: In step (1), the amount of magnesium oxide added is n(MgO):n(Co)=0.6-0.8:1, and the reaction time is 10-30 min.

8. The application method according to claim 5, characterized in that: In step (1), the solid content of magnesium oxide is 10%, and the slurry preparation time is 5-30 minutes.

9. The application method according to claim 5, characterized in that: In step (2), vacuum filtration is used for solid-liquid separation, the drying temperature is 60-80° C., the cobalt recovery rate is above 60%, and the cobalt grade is above 35%.

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