Green diamond purification process

Abstract

The invention relates to subsequent processing of artificial diamonds, in particular to a green diamond purification process which comprises the following steps: crushing a synthetic diamond block and then loading the crushed synthetic diamond block into an anode bag; putting the anode bag into an electrolytic bath for electrolysis; the electrolyzed diamond particles are taken out of the anode bag and then put into a ball mill to be subjected to ball milling; the ball-milled diamond particles are conveyed to a cyclone separator to be subjected to cyclone separation; and mechanically washing and drying the diamond particles obtained by cyclone separation to obtain pure diamond particles. According to the method, the diamond is purified for multiple times by adopting an electrolytic method, cyclone separation and the like, and the electrolyte does not contain high-strong acid such as sulfuric acid and nitric acid, so that the cost is relatively low, the product purity is high, and the method is green and environment-friendly; meanwhile, through the circulating process of rotational flow and elutriation, the recovery rate of the diamond can be increased, the cost can be further reduced, and the purpose of green purification is achieved.

Description

Technical Field

[0001] The invention relates to post-processing of artificial diamonds, in particular to a green diamond purification process. Background Art

[0002] At present, synthetic diamond blocks need to be purified because they contain graphite, catalyst metals, etc. The commonly used purification method is to use the strong oxidizing properties of concentrated sulfuric acid, perchloric acid, nitric sulfuric acid, etc. to react with catalyst metals and graphite to achieve the purpose of impurity removal and purification. This method is not only complicated in process, high in material consumption, labor-intensive, and costly, but also produces a large amount of harmful acidic gas, acid-containing wastewater, and solid waste containing a large amount of iron and nickel, which seriously pollutes the environment. Electrolytic purification of diamond has also appeared on the market. This method is to oxidize the catalyst metal into metal ions and then dissolve it in the electrolyte, and then reduce and recover metal nickel, iron, etc. on the cathode. It has high economic value and is gradually being promoted and applied. However, the existing diamond electrolytic purification mostly uses electrolytes of nickel sulfate system and hydrochloric acid system, which cannot completely dissolve the catalyst metal and need to boil acid; and the diamond obtained by electrolysis is basically separated from graphite by a shaking table, which has too low production efficiency, large water consumption, and large floor space; at the same time, it is difficult to solve the problems of manual washing and labor-consuming time. Summary of the invention

[0003] In response to the above technical problems, the present invention provides a green diamond purification process with low cost and high purification quality.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: a green diamond purification process, which comprises the following steps: (1) Crushing the synthetic diamond blocks and putting them into anode bags; (2) placing the anode bag into an electrolytic cell for electrolysis; (3) taking the electrolyzed diamond particles out of the anode bag and placing them in a ball mill for ball milling; (4) transporting the milled diamond particles to a cyclone separator for cyclone separation; (5) Mechanically washing and drying the diamond particles obtained by the cyclone separation to obtain pure diamond particles.

[0005] Preferably, the electrolyte used in the electrolytic cell is a mixed solution consisting of citric acid, ammonium chloride, iron, nickel, cobalt and copper.

[0006] Preferably, the electrolyte comprises 50-100 parts by mass of citric acid, 75-150 parts by mass of ammonium chloride, 10-20 parts by mass of iron, 20-25 parts by mass of nickel, 0.01-0.03 parts by mass of cobalt, and 0.01-0.03 parts by mass of copper, and the current density is 0.5-6A / dm 2Electrolysis for 72-120 hours.

[0007] Preferably, the ball mill is used for 2-3 hours, and the weight ratio of the ball to the material is 4:1.

[0008] Preferably, the electrolyte in the electrolyte pool is transported to a plurality of electrolytic cells, and after each electrolytic cell completes electrolysis, the electrolyte therein flows back to the electrolyte pool through a circulation pipeline.

[0009] Preferably, during electrolysis, the gas generated by each electrolytic cell is pumped to a water vapor cooling tower through a fan installed on an air duct and then discharged after being treated.

[0010] Preferably, each electrolytic cell is cleaned with water transported from a water tank, and the cleaned water is transported to the water vapor cooling tower to treat the gas therein, and the water after treating the gas in the water vapor cooling tower is transported to the circulation pipeline.

[0011] Preferably, the ball-milled diamond particles are first added to a feed pump pool, then mixed and stirred into slurry by a feed agitator, and then the slurry is transported to the cyclone separator disposed on the upper side of the feed pool by a feed pump for cyclone separation.

[0012] Preferably, the upper feed port of the cyclone separator is connected to a separator on which a pressure gauge is installed; the slurry delivered by the feed pump is transported through the separator to the cavity of the cyclone separator for cyclone separation, thereby obtaining graphite material from the top of the cyclone separator and diamond material from the bottom, and the diamond material flows into the sand settling hopper on the lower side, and then flows into the washing tank from the sand settling hopper for mechanical washing.

[0013] Preferably, a washing agitator is installed on the washing tank, and a discharge hopper is provided at the bottom of the washing tank. The washing agitator stirs and washes the diamond material in the washing tank with clean water, thereby obtaining graphite washing liquid from the upper part of the washing tank. The washed diamonds settle to the discharge hopper and then enter the inclined discharge pipe. The diamond particles are then collected from the discharge pipe and dried or transported to the separator for cyclone separation again.

[0014] From the above technical scheme, it can be seen that the present invention uses electrolysis and cyclone separation to purify diamond multiple times, and the electrolyte does not contain high-strength acids such as sulfuric acid and nitric acid. It is not only low in cost and high in product purity, but also green and environmentally friendly. At the same time, the present invention can not only improve the recovery rate of diamonds through the circulation process of cyclone and washing, but also further reduce costs to achieve the purpose of green purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of the electrolysis process of the present invention.

[0016] Figure 2 It is a schematic flow diagram of the cyclone separation process of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below in conjunction with the accompanying drawings. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0018] The present invention provides a green diamond purification process, which comprises the following steps: First, artificial synthetic diamond blocks are crushed into particles with a particle size of less than 5 mm, and then loaded into an anode bag; the anode bag is then placed in an electrolytic cell, the anode electrode is a graphite sheet, the cathode electrode is a 20mm×100mm×2mm titanium plate, and then an electrolyte is prepared according to the mass fractions of citric acid 50-100 parts, ammonium chloride 75-150 parts, iron 10-20 parts, nickel 20-25 parts, cobalt 0.01-0.03 parts, and copper 0.01-0.03 parts, and then the electrolyte is added to the electrolytic cell with a current density of 0.5-6A / dm 2 Electrolysis is performed at 50-80°C for 72-120 hours, thereby completely dissolving the diamond particles, refining the graphite, and further separating the catalyst metals such as nickel and iron.

[0019] The citric acid in the electrolyte of the present invention is Ni 2+ and Fe 2+ complexing agent, while citric acid can also prevent Fe 2+ Oxidized to Fe 3+ , so that the impurity removal ability of the electrolyte is enhanced and the pH value of the electrolyte is stabilized. Among them, ammonium chloride has good electrical conductivity in the electrolyte, and can form a relatively stable complex with Fe and Ni ions. The complex can prevent Fe and Ni ions from being oxidized and decomposed in an acidic environment, and can prevent Fe and Ni ions from being hydrolyzed into hydroxides and precipitated in an alkaline environment, so that the electrolyte is maintained in a stable working state. And the electrolyte contains very little copper, which is easier to deposit than iron and nickel, and can improve the electrolysis effect. From the above, it can be seen that the electrolyte of the present invention does not use strong acids and alkalis, which not only saves costs, but is also green and environmentally friendly.

[0020] like Figure 1As shown, the electrolyte in the electrolyte pool 21 of the present invention is transported to several electrolytic cells 22. After each electrolytic cell completes electrolysis, the electrolyte in it flows back to the electrolyte pool through the circulation pipe 23, thereby realizing the recycling of the electrolyte, which not only reduces environmental pollution but also saves costs. During electrolysis, the gas generated by each electrolytic cell is pumped to the water vapor cooling tower 26 through the fan 25 set on the air duct 24 for treatment and then discharged to further reduce environmental pollution; at the same time, the water transported by the water tank 27 cleans each electrolytic cell, and the cleaned water is transported to the water vapor cooling tower to treat the gas therein. The water after treating the gas in the water vapor cooling tower is transported to the circulation pipe, and then flows back to the electrolyte pool together with the recycled electrolyte, thereby realizing double recycling, further reducing costs and reducing pollution.

[0021] Next, the electrolyzed diamond particles are taken out from the anode bag and then placed in a ball mill for ball milling for 2 to 3 hours, with a ball-to-material weight ratio of 4:1, thereby further refining the diamond particles; the ball-milled diamond particles are then added to the feed pump pool and mixed into a slurry to achieve cyclone separation. The specific process is as follows: like Figure 2 , add solvent into the feed pump pool 1 to mix and stir the diamond particles into slurry through the feed stirrer 2, and then use the feed pump 3 to transport the slurry to the cyclone separator 6 arranged on the upper side of the feed pool for cyclone separation. Preferably, the upper feed port of the cyclone separator 6 is connected to a separator 5, and a pressure gauge 4 is installed on the separator, so that the particle size of the diamond particles separated by cyclone separation can be adjusted by controlling the pressure of the feed pump; the slurry transported by the feed pump is transported to the cavity of the cyclone separator through the separator for cyclone separation, so that under the action of the cyclone, a lighter graphite material can be obtained from the top of the cyclone separator, and a heavier diamond material can be obtained from the bottom. In the implementation process, since the graphite is electrolytically refined by the electrolyte of the present invention, and the graphite is further refined by ball milling, it is more conducive to separating the double-refined graphite under the action of the cyclone. The present invention adopts cyclone separation to replace the traditional shaking table for graphite separation, which not only has high production efficiency, small water consumption and high recovery rate, but also has a small equipment footprint, thus greatly saving costs.

[0022] Furthermore, under the action of gravity, the diamond material obtained by cyclone separation flows into the sand settling hopper 7 on the lower side, and then flows into the washing tank 9 from the sand settling hopper. This process does not require additional power, which saves energy consumption and reduces costs. The washing tank 9 of the present invention is equipped with a washing agitator 8, and a discharge hopper 10 is provided at the bottom of the washing tank. After the washing agitator stirs and washes the diamond material in the washing tank with clean water, a graphite washing liquid is obtained from the upper part of the washing tank, thereby further separating the graphite; the washed diamond settles to the discharge hopper 10, and then flows out through the inclined discharge pipe 11, further realizing the powerless output of diamond particles, further reducing costs. Therefore, the present invention replaces the traditional manual washing with mechanical washing, thereby solving the problem of labor-consuming time.

[0023] During the implementation process, the diamond particles after mechanical washing can be directly dried to obtain pure diamond products according to the processing requirements; they can also be transported to the feeder for cyclone separation, mechanical washing, etc. to achieve cyclic purification, so as to obtain higher-grade diamond products. The present invention also collects and filters the graphite slurry obtained from the cyclone separator and the graphite washing liquid obtained from the washing tank to obtain graphite with smaller particle size. It can be seen that the present invention does not use high-strength acids such as sulfuric acid and nitric acid, which can not only reduce emissions and achieve green purification, but also after electrolysis, ball milling, cyclone separation, washing and other processes, the product has high purity, high recovery rate, and low overall processing cost. Example

[0024] Take 20kg of artificial diamond blocks and crush them into about 5mm particles, then put them into the anode bag. The anode electrode is a graphite sheet, and the cathode electrode is a 200mm×1000mm×2mm titanium plate. Then, according to the mass parts of 80 parts of citric acid, 100 parts of ammonium chloride, 15 parts of iron, 20 parts of nickel, 0.01 parts of cobalt, and 0.01 parts of copper, 500L of electrolyte is prepared and added to the electrolytic cell at a current density of 4A / dm 2 Electrolysis was performed at 70°C for 96 hours, and then the particles in the anode bag were taken out and put into a ball mill for 3 hours at a ball-to-material weight ratio of 4:1. The milled particles were then added to a stirring tank and mixed into a slurry, and then pumped to a cyclone separator for separation, followed by mechanical washing and drying to obtain diamond particles. It was observed that the surface of the purified diamond was smooth, free of impurities such as graphite and catalyst metal, and pure and transparent; at the same time, the cathode metal recovery rate was almost 100%, and the graphite recovery rate was almost 100%.

Claims

1. A green diamond purification process, Its characteristics include the following steps: (1) Crushing the synthetic diamond blocks and putting them into anode bags; (2) placing the anode bag into an electrolytic cell for electrolysis; (3) taking the electrolyzed diamond particles out of the anode bag and placing them in a ball mill for ball milling; (4) transporting the milled diamond particles to a cyclone separator for cyclone separation; (5) Mechanically washing and drying the diamond particles after the cyclone separation to obtain pure diamond particles.

2. The green diamond purification process according to claim 1, characterized in that: The electrolyte used in the electrolytic cell is a mixed solution consisting of citric acid, ammonium chloride, iron, nickel, cobalt and copper.

3. The green diamond purification process according to claim 2, characterized in that: The electrolyte is composed of 50-100 parts of citric acid, 75-150 parts of ammonium chloride, 10-20 parts of iron, 20-25 parts of nickel, 0.01-0.03 parts of cobalt, and 0.01-0.03 parts of copper, and the current density is 0.5-6A / dm 2 Electrolysis for 72-120 hours.

4. The green diamond purification process according to claim 1, characterized in that: The ball mill is used for ball milling for 2-3 hours, and the weight ratio of the ball to the material is 4:

1.

5. The green diamond purification process according to any one of claims 1 to 4, characterized in that: The electrolyte in the electrolyte pool is transported to a plurality of electrolytic cells. After each electrolytic cell completes electrolysis, the electrolyte in the electrolytic cell flows back to the electrolyte pool through a circulation pipeline.

6. The green diamond purification process according to claim 5, characterized in that: During electrolysis, the gas generated by each electrolytic cell is pumped to the water vapor cooling tower through a fan installed on the air duct and then discharged outside after treatment.

7. The green diamond purification process according to claim 6, characterized in that: Each electrolytic cell is cleaned with water delivered by the water tank, and the cleaned water is delivered to the water vapor cooling tower to treat the gas therein, and the water after treating the gas in the water vapor cooling tower is delivered to the circulation pipeline.

8. The green diamond purification process according to any one of claims 1 to 4, characterized in that: Firstly, the ball-milled diamond particles are added to the feed pump pool, and then mixed and stirred into slurry by the feed stirrer, and then the feed pump is used to transport the slurry to the cyclone separator arranged on the upper side of the feed pool for cyclone separation.

9. The green diamond purification process according to claim 8, characterized in that: The upper feed port of the cyclone separator is connected to a separator, on which a pressure gauge is installed; the slurry delivered by the feed pump is transported through the separator to the cavity of the cyclone separator for cyclone separation, thereby obtaining graphite material from the top part of the cyclone separator and diamond material from the bottom part, and the diamond material flows into the sand settling hopper on the lower side, and then flows into the washing tank from the sand settling hopper for mechanical washing.

10. The green diamond purification process according to claim 9, characterized in that: The washing tank is provided with a washing agitator, and a discharge hopper is provided at the bottom of the washing tank. The washing agitator stirs and washes the diamond material in the washing tank with clean water, thereby obtaining graphite washing liquid from the upper part of the washing tank. The washed diamonds settle to the discharge hopper and then enter the inclined discharge pipe. The diamond particles are then collected from the discharge pipe and dried or transported to the ore separator for cyclone separation again.

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