A method of recycling of laterite nickel ore hydrometallurgical wastewater

Abstract

This application disclosed a method of recycling the cycle of metallurgical wastewater of laterite nickel ore wet water, including the following steps: take laterite nickel ore high-pressure acid immersion fluid for circulating, CCD washing, iron aluminum and sinking MHP treatment; Filter to obtain the MHP sediment solution; Add alkali to the effluent to remove manganese, and filter to obtain MHP wastewater after manganese removal; Perform ion exchange to recover nickel and cobalt from the wastewater after removing manganese from MHP, obtain the ion exchanged solution and enriched nickel cobalt solution, and reuse the enriched nickel cobalt solution in the CCD washing process; After ion exchange, the liquid is subjected to extraction or ion selective membrane treatment to obtain magnesium rich and magnesium poor solutions; Part of the magnesium rich solution is reused in the MHP precipitation process, while the remaining part is evaporated and crystallized to obtain magnesium sulfate; The lean magnesium solution is electrolyzed by bipolar membrane, and the sodium hydroxide solution obtained is reused for iron and aluminum removal and MHP precipitation processes, while the sulfuric acid solution is reused for high-pressure acid leaching processes. This application improves the recovery and utilization rate of wastewater from wet metallurgy of laterite nickel ore, and the recovered intermediate products can be further purified or directly reused in the preliminary process.

Description

[0001] Description

[0002] A METHOD OF RECYCLING OF LATERITE NICKEL ORE HYDROMETALLURGICAL

[0003] WASTEWATER

[0004] FILED OF DISCLOSURE

[0005] This application belongs to the field of hydrometallurgical , especially involving a method of circulating the recycling method of hydrometallurgical , wastewater in laterite nickel ore .

[0006] BACKGROUND

[0007] During the hydrometallurgical process of extracting valuable metals such as nickel and cobalt from laterite nickel ore , it is inevitable to produce wastewater containing complex metal ions such as Ni , Co , Mn, Mg, Fe , Zn, Al , etc . These wastewater not only contain potential resources , but may also become a source of environmental pollution . Therefore , ef fective recycling and utili zation of them is not only a consideration of economic benefits , but also an urgent need for environmental protection .

[0008] In the process of preparing MHP (nickel cobalt hydroxide ) intermediate products from laterite nickel ore by hydrometallurgy, commonly used precipitants include sodium hydroxide and magnesium oxide . However, the use of sodium hydroxide in industrial production can cause the reaction system to become excessively alkaline locally, which not only increases the manganese content in MHP, but also correspondingly reduces the nickel and cobalt content . The increase in manganese content will increase the cost of subsequent refining steps . In addition, the excessively alkaline environment also accelerates the nucleation rate of MHP, resulting in smaller and unevenly distributed particles . This makes it di f ficult for MHP to ef fectively settle and filter, leading to a higher moisture content in the filter cake and increasing the transportation cost of MHP . In addition, in the existing process , when the nickel cobalt precipitation is completely separated, the filtrate in this step mainly contains Mn and Mg elements . In the process of wastewater treatment , speci fic precipitants are usually used to precipitate manganese , and then the generated manganese slag is filtered and buried . The filtrate after manganese slag filtration mainly contains Mg . Due to the alkaline nature of the filtrate , sul furic acid i s generally used for neutrali zation treatment before discharging it into the ocean . It can be seen that the existing hydrometallurgical wastewater treatment technology for laterite nickel ore still has shortcomings , and new pollutants are often generated during the wastewater treatment process , which has adverse ef fects on the environment . Although various technologies and methods have been applied to the treatment and recycling of such wastewater, there are still some challenges , such as high treatment costs , compatibility issues between technologies , and the risk of secondary pollution . Therefore , how to improve the recycling rate of wastewater and reduce its impact on the environment is a research topic worth exploring in depth .

[0009] SUMMARY

[0010] In response to the shortcomings of existing technology, the purpose of this application is to provide a method for recycling wastewater from hydrometallurgy of laterite nickel ore , aiming to solve the problems of low treatment ef ficiency and secondary pollution in the treatment of laterite nickel ore hydrometallurgy wastewater in existing technology .

[0011] This application is speci fically implemented through the following technical solutions :

[0012] A method for recycling wastewater from hydrometallurgy of laterite nickel ore , comprising the following steps :

[0013] ( 1 ) Take high-pressure acid leaching solution of laterite nickel ore for cyclic leaching, CCD washing, iron and aluminum removal , and MHP precipitation treatment , and filter to obtain the MHP precipitation solution; Add alkali to the solution after MHP sedimentation to remove manganese , and filter to obtain the wastewater after MHP sedimentation and manganese removal ;

[0014] ( 2 ) Perform ion exchange on the wastewater after removing manganese from MHP to obtain the ion exchanged solution and enriched nickel cobalt solution . The enriched nickel cobalt solution is reused in the CCD washing process ; ( 3 ) After ion exchange , the liquid is subj ected to extraction or ion selective membrane treatment to obtain magnesium rich and magnesium poor solutions ; Part of the magnesium rich solution is reused in the MHP precipitation process , while the remaining part is evaporated and crystalli zed to obtain magnesium sul fate ;

[0015] ( 4 ) The lean magnesium solution is electrolyzed by bipolar membrane , and the sodium hydroxide solution obtained is reused for iron and aluminum removal and MHP precipitation processes , while the sul furic acid solution is reused for high-pressure acid leaching processes .

[0016] This application uses ion exchange to recover nickel and cobalt from the wastewater after manganese removal by MHP sedimentation . This not only reduces the nickel and cobalt content in the wastewater, but also meets environmental requirements . Subsequently, the recovered nickel and cobalt after ion exchange are returned to CCD washing, which can improve the utili zation rate of nickel and cobalt . Separate magnesium salts and sodium salts by using extraction or ion selective membrane technology . Sodium salt is converted into sodium hydroxide solution and sul furic acid solution by bipolar membrane electrolysis . The former is partially reused in the iron and aluminum removal process ( as a neutrali zing agent ) , and partially used together with magnesium salt in the manganese precipitation process ( as a precipitant ) ; The latter is reused in the high-pressure acid leaching process , and the remaining magnesium salt is recovered as magnesium sul fate through evaporation crystalli zation . The intermediate products recovered by the recycling method of this application can be further puri fied or extracted to obtain corresponding products , or directly reused in the pre process of wet metallurgy, so that SO42~, Na+, Mg2+, OH~, Ni2+, Co2+and other substances in the wastewater can be directly reused, with high atomic utili zation ef ficiency . In addition, the present application utili zes the above-mentioned method to recycle OH~, Na+, Mg2+from wastewater and use them in the MHP sedimentation process . The final MHP product obtained has comparable or even better performance than products prepared using industrial grade sodium hydroxide and magnesium oxide , and signi ficantly reduces production costs . Preferably, the pH value for the iron and aluminum removal process in step (1) is set to 3.8~5.5.

[0017] Preferably, the pH value of the MHP precipitation process in step (1) is set to 6.3~8.5.

[0018] The preferred method for removing manganese from the solution after MHP precipitation in step (1) is to adjust the pH of the solution to 9.5-11 by adding alkali.

[0019] The specific operation of ion exchange to obtain the ion exchanged solution and enriched nickel cobalt solution from the manganese removed wastewater of MHP in step (2) includes: sending the manganese removed wastewater of MHP to a resin adsorption column to obtain nickel cobalt adsorption resin and ion exchanged solution, and using a desorption agent to desorb the nickel cobalt adsorption resin to obtain enriched nickel cobalt solution.

[0020] Preferably, the resin adsorption column uses cationic resin or chelating resin; More preferably, the cation resin is a strong acidic cation exchange resin, and the chelating resin is M4195 chelating ion exchange resin or IRC-748 chelating ion exchange resin .

[0021] Preferably, the desorbent is an inorganic acid, and the concentration of H+in the desorbent is > O.Olmol / L; More preferably, the inorganic acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid.

[0022] The specific operation for obtaining rich magnesium solution and lean magnesium solution by extracting the ion exchanged liquid in step (3) includes: first, using an extractant to extract the ion exchanged liquid, separating the organic phase and the residual solution, then acid washing the organic phase, and finally using a reverse extractant for reverse extraction. The obtained reverse extractant is the rich magnesium solution, and the residual solution is the lean magnesium solution.

[0023] The preferred extractant is BC196 extractant, the diluent is kerosene, the saponification rate is 25-40%, the O / A ratio is 1- 3, and the extraction stage is 3-8.

[0024] Preferably, the specific operation of acid washing the organic phase includes: using inorganic acid with a concentration of 0.1- 0.8 mol / L for washing, with a washing stage of 6-10; The inorganic acid is at least one of hydrochloric acid and sulfuric acid. Preferably, the specific operation of using a reverse extraction agent for reverse extraction includes: using an inorganic acid with a concentration of 3.0-6.5mol / L for reverse extraction, with a reverse extraction order of 4-8 levels; The inorganic acid is sulfuric acid.

[0025] The specific operation of obtaining magnesium rich and magnesium poor solutions by treating the ion exchanged solution with an ion selective membrane in step (3) includes using an ion selective membrane to separate monovalent and divalent metal ions in the ion exchanged solution. Specifically, the available ion selective membrane can be the CIMS series products sold by Hangzhou Lanran Technology Co., Ltd., a Chinese manufacturer.

[0026] Preferably, the sodium hydroxide solution described in step (4) is mixed with a portion of the magnesium rich solution described in step (3) and then reused in the MHP precipitation process.

[0027] In the MHP sedimentation process, this application pre mixes sodium hydroxide with some magnesium rich solution to generate magnesium hydroxide. Magnesium hydroxide, as a weakly alkaline substance, can avoid or reduce the effect of "local alkalinity" caused by the use of sodium hydroxide alone, thereby achieving a moderate nucleation rate of MHP and producing particles of appropriate size and uniform distribution. This not only effectively reduces the moisture content of the filter cake, but also helps to lower the transportation cost of MHP.

[0028] Preferably, when the sodium hydroxide solution described in step (4) is mixed with the partially enriched magnesium solution described in step (3) , the ratio of Na+in the sodium hydroxide solution to Mg2+in the partially enriched magnesium solution is 1:1 to 9.

[0029] In this application, the mixture of magnesium rich solution and sodium hydroxide will generate magnesium hydroxide, which is a weakly alkaline substance. Relying solely on magnesium hydroxide as a precipitant can result in higher magnesium content and lower nickel content in the prepared MHP, thereby increasing the transportation cost of MHP and the cost of using P507 extractant to remove magnesium during subsequent refining processes. Therefore, this application achieves the coexistence of sodium hydroxide and magnesium hydroxide by controlling the molar ratio of Na+in sodium hydroxide solution to Mg2 +in magnesium rich solution to be 1 : 1~ 9 , and uses it as a mixed precipitant to participate in the precipitation process of MHP .

[0030] Compared with exi sting technologies , the beneficial ef fects of this application include :

[0031] The present invention first performs ion exchange on the wastewater after manganese removal from MHP to recover nickel and cobalt , and produces ion exchanged liquid and enriched nickel cobalt solution . The enriched nickel cobalt solution is reused in the CCD washing process . Subsequently, the ion exchanged solution is separated into magnesium salts and sodium salts through extraction or ion selective membrane technology . Among them, sodium salt is converted into sodium hydroxide solution and sul furic acid solution through bipolar membrane electrolysis technology . The sul furic acid solution is reused in the high- pressure acid leaching process ; A portion of the sodium hydroxide solution is reused in the iron and aluminum removal process , while another portion is mixed with some magnesium salts and reused in the manganese precipitation MHP process . The remaining magnesium salts are recovered as magnesium sul fate through evaporation crystalli zation . The present invention achieves a high recovery and utili zation rate for the wastewater after manganese removal by MHP sedimentation . The intermediate products obtained from recycling can be further puri fied or extracted to obtain corresponding products , or directly reused in the pre process of hydrometallurgy . The entire recycling process has a relatively small impact on the environment .

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG . 1 is a schematic diagram of the first embodiment of the method for recycling wastewater from hydrometallurgy of laterite nickel ore in the present application .

[0034] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] In order to clari fy the purpose , technical solution, and advantages of this application, further detailed explanations will be provided below in conj unction with the embodiments . It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0036] The main components of the iron and aluminum removed solution of laterite nickel ore used in the following embodiments and comparative examples of the present invention are as follows: nickel ions are 3.43 g / L, cobalt ions are 0.351 g / L, manganese ions are 2.25 g / L, calcium ions are 0.589 g / L, and magnesium ions are 7.99 g / L .

[0037] Example 1

[0038] A method for recycling wastewater from hydrometallurgy of laterite nickel ore, comprising the following steps:

[0039] (1) Take high-pressure acid leaching solution of laterite nickel ore for cyclic leaching, CCD washing, iron and aluminum removal, and MHP precipitation treatment, and filter to obtain the MHP precipitation solution; Add alkali (sodium hydroxide) to the effluent to adjust the pH to 9.5-11 in order to remove manganese, and filter to obtain MHP wastewater after manganese removal; Among them, the pH control for the iron and aluminum removal process is 3.8~5.5; Control the pH of the MHP process at 6.3-8.5 and react for 5 hours at 60 °C;

[0040] (2) After removing manganese from the MHP sediment, the wastewater is sent to the M4195 chelating ion exchange resin adsorption column to obtain nickel cobalt adsorption resin and ion exchange solution. Hydrochloric acid is used as the desorbent to desorb the nickel cobalt adsorption resin. The concentration of H+in hydrochloric acid is > O.Olmol / L to obtain an enriched nickel cobalt solution; The enriched nickel cobalt solution is reused in the CCD washing process ;

[0041] The main components of the liquid after ion exchange are as follows: divalent ions such as Ni, Co, Mn, etc. are all less than 0. Img / L .

[0042] (2) Firstly, BC196 extractant was used to extract the ion exchanged liquid, with kerosene as the diluent, a saponification rate of 30%, an O / A ratio of 3, and an extraction stage of 8; Separate the organic phase and the residual solution, then wash the organic phase with a sulfuric acid solution with a concentration of O.lmol / L in 8 stages. Finally, use a sulfuric acid solution with a concentration of 3.0mol / L for back extraction in 6 stages, and the resulting back extraction solution is a magnesium rich solution, while the residual solution is a magnesium poor solution; Part of the rich magnesium solution is reused in the MHP precipitation process, while the remaining part is evaporated and crystallized to obtain magnesium sulfate;

[0043] (3) After bipolar membrane electrolysis treatment, the lean magnesium solution is treated to obtain sodium hydroxide solution and sulfuric acid solution. The sulfuric acid solution is reused in the high-pressure acid leaching process, and a portion of the sodium hydroxide solution is reused in the iron and aluminum removal process. The other portion is mixed with the magnesium rich solution described in step (3) and reused in the MHP precipitation process. The ratio of Na+in the sodium hydroxide solution to Mg2+in the magnesium rich solution is controlled to be 1:1, and the ratio of the sum of the molar amounts of sodium and magnesium elements to the sum of the molar amounts of nickel and cobalt elements in the solution after iron and aluminum removal of laterite nickel ore satisfies: (Na * 2+Mg) / (Ni+Co)=l. Example 2

[0044] This embodiment provides a method for recycling wastewater from hydrometallurgy of laterite nickel ore, which differs from embodiment 1 only in that:

[0045] In step (4) , the ratio of Na+in the sodium hydroxide solution to Mg2+in the magnesium rich solution was controlled to 1:5, and the other steps and conditions were the same as in Example 1. Example 3

[0046] This embodiment provides a method for recycling wastewater from wet metallurgy of laterite nickel ore, which differs from embodiment 1 only in that: In step (4) , the ratio of Na+in the sodium hydroxide solution to Mg2+in the magnesium rich solution was controlled to be 1:9, and the other steps and conditions were the same as in Example 1. Comparative Example 1

[0047] The only difference from Example 1 is that the wastewater after manganese removal in MHP is reused in the MHP process, while other steps and conditions are the same as in Example 1. Comparative Example 2 The only di f ference from Example 1 is that industrial grade sodium hydroxide and magnesium oxide are used instead of the sodium hydroxide solution obtained by bipolar membrane electrolysis and the magnesium rich solution obtained by extraction, respectively . Other steps and conditions are the same as Example 1 .

[0048] The above embodiments and comparative examples were basically stable after 10 cycles of operation . At this time , the composition content , particle si ze , and moisture content of the MHP filter cake produced by the sedimentation MHP process after the 10th cycle were tested . The test results are shown in Table 1 .

[0049] Table 1 : Statistical Table of MHP Filter Cake Composition, Particle

[0050] Si ze , and Moisture Content

[0051] From the results in Table 1 , it can be seen that the MHP filter cake prepared by recycling the wastewater from hydrometallurgy of laterite nickel ore using the method described in the present invention has good performance . Compared with the comparative method, the MHP filter cake prepared in this application has better performance .

[0052] The speci fic implementation methods described above do not constitute a limitation on the scope of protection of this application . Any other corresponding changes and modi fications made based on the technical concept of this application shall be included within the scope of protection of the claims of this application .

Claims

WHAT IS CLAIMED IS l. A method for recycling wastewater from hydrometallurgy of laterite nickel ore, which is characterized by the following steps:(1) Take high-pressure acid leaching solution of laterite nickel ore for cyclic leaching, CCD washing, iron and aluminum removal, and MHP precipitation treatment, and filter to obtain the MHP precipitation solution; Add alkali to the solution after MHP sedimentation to remove manganese, and filter to obtain the wastewater after MHP sedimentation and manganese removal;(2) Perform ion exchange on the wastewater after removing manganese from MHP to obtain the ion exchanged solution and enriched nickel cobalt solution. The enriched nickel cobalt solution is reused in the CCD washing process;(3) After ion exchange, the liquid is subjected to extraction or ion selective membrane treatment to obtain magnesium rich and magnesium poor solutions; Part of the magnesium rich solution is reused in the MHP precipitation process, while the remaining part is evaporated and crystallized to obtain magnesium sulfate;(4) The lean magnesium solution is electrolyzed by bipolar membrane, and the sodium hydroxide solution obtained is reused for iron and aluminum removal and MHP precipitation processes, while the sulfuric acid solution is reused for high-pressure acid leaching processes .

2. The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 1, characterized in that the pH value of the iron and aluminum removal process in step (1) is set to 3.8~5.5 ;The pH value of the MHP precipitation process in step (1) is set to 6.3~8.5;The method of adding alkali to remove manganese in the solution after MHP precipitation as described in step (1) is to adjust the pH of the solution to 9.5-11 by adding alkali.

3. The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 1, characterized in that the specific operation of ion exchange to obtain ion exchangedliquid and enriched nickel cobalt solution from the wastewater after manganese removal of MHP in step ( 2 ) includes : sending the wastewater after manganese removal of MHP to a resin adsorption column to obtain nickel cobalt adsorption resin and ion exchanged liquid, and using a desorbent to desorb the nickel cobalt adsorption resin to obtain enriched nickel cobalt solution .4 . The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 3 , characteri zed in that the resin adsorption column adopts cationic resin or chelating resin;The desorbent is an inorganic acid, and the concentration of H+in the desorbent is > O . O lmol / L .5 . The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 4 , characteri zed in that the cation resin is a strong acidic cation exchange resin, and the chelating resin is M4195 chelating ion exchange resin or IRC-748 chelating ion exchange resin;The inorganic acid is at least one of sul furic acid, hydrochloric acid, and nitric acid .6 . The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 1 , characteri zed in that the speci fic operation of extracting the ion exchanged liquid to obtain rich magnesium solution and poor magnesium solution in step ( 3 ) includes : first , using an extractant to extract the ion exchanged liquid, separating the organic phase and the extraction residue , then acid washing the organic phase , and finally using a reverse extractant for reverse extraction, the obtained reverse extractant is the rich magnesium solution, and the extraction residue is the poor magnesium solution;The speci fic operation of obtaining rich magnesium solution and poor magnesium solution by treating the ion exchanged liquid through ion selective membrane in step ( 3 ) includes : using ion selective membrane to separate monovalent metal ions and divalent metal ions in the ion exchanged liquid .

7. The method for recycling wastewater from wet metallurgy of laterite nickel ore according to claim 6, characterized in that the extractant is BC196; The diluent is kerosene, with a saponification rate of 25-40%, an O / A ratio of 1-3, and extraction stages of 3-8;The specific operation of acid washing the organic phase includes: using inorganic acid with a concentration of 0.1-0.8 mol / L for washing, with a washing stage of 6-10; The inorganic acid is at least one of hydrochloric acid and sulfuric acid.The inorganic acid is at least one in sulfuric acid, hydrochloric acid and nitric acid.

8. The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 6 or 7, characterized in that the specific operation of using a reverse extraction agent for reverse extraction includes: using inorganic acid with a concentration of 3.0-6.5mol / L for reverse extraction, with a reverse extraction stage of 4-8; The inorganic acid is sulfuric acid .

9. The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 1, characterized in that the sodium hydroxide solution in step (4) is mixed with the partially magnesium rich solution in step (3) and then reused in the MHP precipitation process.

10. The method for recycling wastewater from hydrometallurgy of laterite nickel ore according to claim 9, characterized in that when the sodium hydroxide solution in step (4) is mixed with the partially rich magnesium solution in step (3) , the ratio of Na+in the sodium hydroxide solution to Mg2+in the partially rich magnesium solution is 1:1~9.

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