A method for preparing MHP by recycling the liquid after manganese precipitation

Abstract

The present invention discloses a method for preparing MHP (Mixed Hydroxide Precipitate) by recycling the liquid after manganese precipitation. The method includes the following steps: Mixing sodium hydroxide (NaOH), magnesium oxide (MgO) and the post-manganese precipitation liquid to obtain a compound alkaline slurry; Mixing the post-iron-aluminum removal liquid of laterite nickel ore and the compound alkaline slurry for precipitation reaction to obtain MHP slurry; Thickening the MHP slurry to obtain thickened underflow; Filtering the thickened underflow to obtain MHP filter cake and filtrate; Directly subjecting the filtrate to manganese precipitation treatment to obtain manganese residue and post-manganese precipitation liquid; Recycling the post-manganese precipitation liquid back to the preparation of the compound alkaline slurry. The invention utilizes a sodium hydroxide and magnesium oxide compound system to simplify the MHP precipitation process to one step. Meanwhile, the post-manganese precipitation liquid is partially recycled back to the alkali preparation process, which not only reduces the cost of wastewater treatment, but also reduces the magnesium content in MHP by controlling the circulation amount of the post-manganese precipitation liquid, thereby reducing the cost of subsequent purification and crystallization preparation of MHP.

Description

[0001] Description

[0002] A METHOD FOR PREPARING MHP BY RECYCLING THE LIQUID AFTER MANGANESE PRECIPITATION

[0003] Field Of The Disclosure

[0004] The present invention relates to the field of hydrometallurgy, speci fically to a method for preparing MHP by recycling the liquid after manganese precipitation .

[0005] Background

[0006] It is well known that the key impurity element monitored is Mg for MHP prepared by laterite nickel ore . High Mg content not only reduces the nickel content in MHP, increasing its transportation cost , but also signi ficantly increases the cost of P507 extraction to separate of nickel and cobalt in the subsequent puri fication process of MHP . Speci fically, the main elements in the post-iron-aluminum removal liquid of laterite nickel ore are Ni , Co , Mn, and Mg, with the Mg concentration being about 2 to 3 times that of Ni . To prepare high-quality MHP and reduce the content of impurity elements , the nickel-cobalt precipitation process is divided into two precipitation stages , wherein the first stage is for product grade . The partical MHP prepared in the second stage is used as the crystal seeds for the precipitation reaction of the stage , while the rest is returned to the previous circulation leaching section to utili ze the residual acid in the high-pressure leaching liquid and leach out nickel and cobalt from MHP . These nickel and cobalt are then re-entered into the next round of nickel-cobalt precipitation process , which seriously af fects the consumption of alkali in the nickel-cobalt precipitation process , thereby increasing the production cost . After the complete precipitation of nickel and cobalt , the main elements in the filtrate of the process section are Mn and Mg . The wastewater treatment end precipitates Mn and then filters , and buries the manganese residue . At this time , the filtrate after the manganese residue filtration mainly contains Mg, and due to its alkaline nature , it is generally treated with sul furic acid to neutrali ze and then re-enter the ocean .

[0007] Currently, sodium hydroxide or MgO are used to prepare MHP in the industry . In addition to the high cost of sodium hydroxide , it is easy to cause the local over-alkalinity, so its amount in the preparation process of MHP is obviously greater than the theoretical calculation one , which is not conducive to reducing the production cost of MHP . MgO is inexpensive , but it is di f ficult to dissolve , so the Mg content for the MHP prepared using MgO is generally high .

[0008] In general , new energy batteries are classi fied as processing and manufacturing industry, mainly because the cost of cathode materials used in the production of new energy batteries accounts for a high proportion . Therefore , on the basis of not af fecting the quality of MHP itsel f , optimi zing the MHP preparation process to greatly reduce the production cost of MHP and then reduce the cost of NCM / NCA new energy batteries is of great signi ficance for promoting mankind to enter the new green energy era .

[0009] Summary

[0010] In view of the deficiencies of the existing technology, the purpose of the present invention is to provide a method for preparing MHP by recycling the liquid after manganese precipitation, addressing the technical problems of high cost , high magnesium content , complicated precipitation process , and inef fective resource utili zation of post-manganese precipitation liquid in the current MHP preparation .

[0011] To achieve the above purpose , the present invention adopts the following technical solutions :

[0012] The present invention provides a method for preparing MHP by recycling the liquid after manganese precipitation, which includes the following steps :

[0013] ( 1 ) Mixing sodium hydroxide , magnesium oxide and the post-manganese precipitation liquid to obtain a compound alkaline slurry; (2) Mixing the post-iron-aluminum removal liquid of laterite nickel ore and the compound alkaline slurry for precipitation reaction to obtain MHP slurry;

[0014] (3) Subjecting the MHP slurry to thickening to obtain thickened underflow;

[0015] (4) Filtering the thickened underflow, and washing the MHP with distilled water or industrial water to obtain MHP filter cake and filtrate ;

[0016] (5) Subjecting the filtrate to manganese precipitation treatment to obtain manganese residue and post-manganese precipitation liquid;

[0017] (6) Recycling the post-manganese precipitation liquid back to the preparation of the compound alkaline slurry.

[0018] The invention utilizes the precipitation balance principle of nickel, cobalt, manganese and magnesium, and takes the combination system of sodium hydroxide and magnesium oxide as the precipitant to simplify the MHP precipitation process to one step. Meanwhile, the post-manganese precipitation liquid is creatively recycled back to the alkali preparation process, which not only reduces the cost of wastewater treatment, but also reduces the magnesium content in MHP by controlling the circulation amount of the post-manganese precipitation liquid, thereby reducing the cost of subsequent purification and crystallization preparation of MHP.

[0019] Preferably, the molar ratio of sodium hydroxide to magnesium oxide is (1:0.1) to (1:4) in step (1) .

[0020] Preferably, the concentration of the compound alkaline slurry is l-15wt% in step (1) .

[0021] Preferably the post-iron-aluminum removal liquid of laterite nickel ore contains 2-8 g / L Ni, 0.15-0.8 g / L Co, 1-6 g / L Mn, and 5-20 g / L Mg in step (2)

[0022] Preferably, the sum of the molar amounts of sodium and magnesium elements in the compound alkaline slurry and the post-iron-aluminum removal liquid of laterite nickel ore satisfies the ratio: (2Na+Mg) / (Ni +Co) = (0.9-1) : (1-1.1) in step (2) .

[0023] Preferably, the temperature of the precipitation reaction is 55-70°C, and the reaction time is 1-8 hours in step (2) .

[0024] Preferably, the concentration of magnesium ions in the post-manganese precipitation liquid is 2-10 g / L in step (5) . The beneficial ef fects of the invention are :

[0025] The utili zes the sodium hydroxide and magnesium oxide compound system as a precipitant , which can simpli fy the MHP precipitation process to one step ; Meanwhile , the post-manganese precipitation liquid is partially recycled back to the alkali preparation process , which not only reduces the cost of wastewater treatment , but also reduces the magnesium content in MHP by controlling the circulation amount of the post-manganese precipitation liquid, thereby reducing the cost of subsequent puri fication and crystalli zation preparation of MHP .

[0026] Brief Description Of The Drawing

[0027] To more clearly illustrate the technical solutions of the invention, a brief introduction to the drawings of the embodiment is provided below .

[0028] Figure l is a flowchart of a method for preparing MHP by recycling the liquid after manganese precipitation according to the present invention .

[0029] Detailed Description Of Preferred Embodiments

[0030] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention . Obviously, the described embodiments are only part of the embodiments of the invention, not all .

[0031] The traditional method of directly adding strong alkaline precipitants is easy to form the local over-alkalinity in the precipitation system . Therefore , when nickel , cobalt and manganese are precipitated, a small part of magnesium ions are also hydrolyzed and nucleated together in a short time . Therefore , in order to produce high-quality MHP, the existing technology usually divides nickel cobalt precipitation into two process stages , and the subsequent manganese solution is di f ficult to ef fectively utili ze afterwards . In view of these , the present invention provides a method for preparing MHP by recycling the liquid after manganese precipitation, which includes the following steps : Mixing sodium hydroxide , magnesium oxide with the post-manganese precipitation liquid to obtain a compound alkaline slurry; Mixing the post-iron-aluminum removal liquid of laterite nickel ore with the compound alkaline slurry for precipitation reaction to obtain MHP slurry; Subj ecting the MHP slurry to thickening to obtain thickened underflow; Filtering the thickened underflow, and washing the MHP with industrial water to obtain MHP filter cake and filtrate ; Subj ecting the filtrate directly to manganese precipitation treatment , to obtain manganese residue and post-manganese precipitation liquid; Recycling the post-manganese precipitation liquid back to the preparation of the compound alkaline slurry . The present invention employs s a sodium hydroxide and magnesium oxide compound system, which can simpli fy the MHP precipitation process to one step . Meanwhile , the post-manganese precipitation liquid is partially recycled back to the alkali preparation process , which not only reduces the cost of wastewater treatment , but also reduces the magnesium content in MHP by controlling the circulation amount of the post-manganese precipitation liquid, thereby reducing the cost of subsequent puri fication and crystalli zation preparation of MHP .

[0032] To make the purpose , technical solutions , and advantages of the present invention clearer, a further detailed description of the embodiments of the present invention will be provided below .

[0033] The red mud nickel ore post-iron-aluminum removal liquid used in the embodiments and Comparisons comes from the solution after high-pressure acid leaching and iron-aluminum removal of red mud nickel ore with the main components of 3 . 45 g / L Ni , 0 . 38 g / L Co , 2 . 59 g / L Mn, 7 . 85 g / L Mg .

[0034] Example 1

[0035] A method for preparing MHP by recycling the liquid after manganese precipitation, including the following steps :

[0036] ( 1 ) Mixing sodium hydroxide and magnesium oxide in a molar ratio of 1 : 1 with the post-manganese precipitation liquid (magnesium ion concentration of 7 g / L ) to obtain a compound alkaline slurry with a concentration of 10wt% .

[0037] ( 2 ) Mixing the compound alkaline slurry with the post-iron-aluminum removal liquid of red mud nickel ore , and reacting at a temperature of 60 ° C for 5 hours to obtain MHP slurry; where the sum of the molar amounts of sodium and magnesium elements in the compound alkaline slurry and the post-iron-aluminum removal liquid of red mud nickel ore meets the ratio : ( 2Na+Mg) / (Ni +Co ) = 1 .

[0038] ( 3 ) Subj ecting the MHP slurry to thickening to separate the supernatant and MHP underflow .

[0039] ( 4 ) Filtering the MHP underflow, and washing the MHP with industrial water to obtain filtrate and MHP filter cake .

[0040] ( 5 ) Adding lime mi lk to the filtrate obtained in step 4 to adj ust the solution pH to 8 . 5 for manganese precipitation, and filtering to obtain manganese residue and post-manganese precipitation liquid .

[0041] ( 6 ) Recycling the post-manganese precipitation liquid back to the preparation process of the compound alkaline slurry in step 1 .

[0042] Example 2 di f fers from Example 1 only in that the post-manganese precipitation liquid is used to adj ust the concentration of the compound alkaline slurry to 15wt% , with other steps and conditions being the same as in Example 1 .

[0043] Example 3 di f fers from Example 1 only in that the post-manganese precipitation liquid is used to adj ust the concentration of the compound alkaline slurry to 5wt% , with other steps and conditions being the same as in Example 1 .

[0044] Comparative Example 1 di f fers from Example 1 only in that the molar ratio of sodium hydroxide to magnesium oxide is adj usted to 1 : 9 , with other steps and conditions being the same as in Example 1 .

[0045] Comparative Example 2 di f fers from Example 1 only in that the post-manganese precipitation liquid is used, with sodium hydroxide alone as the precipitant for preparing the compound alkaline slurry, with other steps and conditions being the same as in Example 1 .

[0046] Comparative Example 3 di f fers from Example 1 only in that the post-manganese precipitation liquid is used, with magnesium oxide alone as the precipitant for preparing the compound alkaline slurry, with other steps and conditions being the same as in Example 1 .

[0047] Performance Testing

[0048] The components of MHP obtained from the embodiments and Comparisons were tested, and the results are shown in Table 1 . Table 1 Precipitation rate of Ni , Co and MHP composition (wt % )

[0049] From Table 1 , it can be seen that comparing Example 1 and Comparative Example 2 , the use of a strong alkaline precipitant results in a higher precipitation rate of manganese and magnesium due to local over-alkalinity, which leads to a higher magnesium content in MHP and correspondingly reduces the precipitation rate of nickel and cobalt .

[0050] Comparing Example 1 and Comparative Example 3 , it can be seen that using magnesium oxide alone as a precipitant makes the precipitation of Ni , Co , Mn, and Mg more inclined to the order of their equilibrium reaction due the control of the rate of the precipitation reaction, thereby reducing the manganese content in MHP, and the precipitation rates of nickel and cobalt are also high . However, due to the incomplete dissolution of MgO in the precipitation reaction, the magnesium content in MHP is over the limit , thereby reducing the nickel content in MHP .

[0051] Comparing Example 1-3 , it can be seen that the quality of MHP is very sensitive to the concentration of sodium hydroxide and magnesium oxide slurry . Appropriately reducing the concentration of sodium hydroxide and magnesium oxide slurry can very ef fectively reduce the Mn and Mg content in MHP and the precipitation rates of nickel and cobalt also increase . When the circulation amount of the post-manganese liquid is increased to reduce the alkali slurry concentration to 5% , the precipitation rates of nickel and cobalt both reach 97 % , and the Mg content in MHP can be reduced to less than 1 . 5% with very high nickel content , making the MHP product quality excellent . Therefore , considering both the precipitation rate of nickel and cobalt and the quality of MHP, one-step precipitation of MHP can be achieved by optimi zing the process conditions for preparing MHP with a sodium hydroxide and magnesium oxide slurry compound system . Moreover, it is not di f ficult to find that the practical precipitation rate of nickel and cobalt in the MHP preparation process of the compound system is very close to the theoretical calculation value , which means that the utili zation rate of the compound alkali in the precipitation reaction process is very high, which can signi ficantly reduce the cost of the nickel and cobalt precipitation process of the MHP product .

[0052] Comparing Comparative Example 1 and Example 1 , it can be seen that when the proportion of magnesium oxide in the compound system is increased to 0 . 9 , the magnesium content in MHP is seriously exceeded, which leads to the obvious reduction of nickel content in MHP, which seriously af fects the quality of MHP . Therefore , it is very important to control the ratio of sodium hydroxide to magnesium oxide in the compound system to improve the quality of MHP .

[0053] It should be noted that the above examples all belong to the same inventive concept , and the descriptions of individual examples have di f ferent focuses . Where the description in individual examples is not exhaustive , references can be made to the descriptions in other examples .

[0054] The above examples only express the implementation of the present invention, which is described more speci fically and in detail , but this should not be understood as a limitation on the scope of the invention patent . It should be pointed out that for ordinary technicians in the field, various modi fications and improvements can still be made without departing from the inventive concept of the present invention, and these all belong to the scope of protection of the present invention . Therefore , the scope of protection of the present invention patent should be determined by the appended claims .

Claims

What Is Claimed Is1. A method for preparing MHP by recycling the liquid after manganese precipitation, characterized by the following steps:(1) Mixing sodium hydroxide and magnesium oxide with the post-manganese precipitation liquid to obtain a compound alkaline slurry;(2) Mixing the post-iron-aluminum removal liquid of laterite nickel ore with the compound alkaline slurry for precipitation reaction to obtain MHP slurry;(3) Subjecting the MHP slurry to thickening to obtain thickened underflow;(4) Filtering the thickened underflow, while washing the MHP with distilled water or industrial water to obtain MHP filter cake and filtrate ;(5) Subjecting the filtrate to manganese precipitation treatment to obtain manganese residue and post-manganese precipitation liquid;( 6) Recycling the post-manganese precipitation liquid back to the preparation of the compound alkaline slurry as described in step (1) .

2. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the molar ratio of sodium hydroxide to magnesium oxide is (1:0.1) to (1:4) in step ( 1 ) .

3. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the concentration of the compound alkaline slurry is l-15wt% in step (1) .

4. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the post-iron-aluminum removal liquid of laterite nickel ore contains 2-8 g / L Ni, 0.15-0.8 g / L Co, 1-6 g / L Mn, and 5-20 g / L Mg in step (2) .

5. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the sum of the molar amounts of sodium and magnesium elements in the compoundalkaline slurry and the post-iron-aluminum removal liquid of laterite nickel ore is in the ratio: (2Na+Mg) / (Ni +Co) = (0.9-1) : (1-1.1) in step (2) .

6. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the temperature of the precipitation reaction is 55-70°C in step (2) .

7. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the reaction time of the precipitation reaction is 1-8 hours in step (2) .

8. A method for preparing MHP by recycling the liquid after manganese precipitation according to claim 1, characterized in that the concentration of magnesium ions in the post-manganese precipitation liquid is 2-10 g / L in step (2) .

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