Gold Creek is a graphite mine reserves of 26 million t of large flake graphite deposit, ore of high graphite content, fixed carbon average grade of 10.18%. The biggest feature of the mine is the high grade of vanadium in the ore. Occurrence of vanadium in the form of vanadium oxide, vanadium white mica, muscovite vanadium assembly with fan-shaped or flaky graphite flake symbiosis, a single wafer diameter of 0.2 ~ 5mm, up to an aggregate of more than 1cm, mostly distributed in parallel along the sheet processing. The content of vanadium and muscovite in graphite ore accounts for 5% to 10%, and the content of V 2 O 5 is 0.4 to 0.7%. This type of associated vanadium resource is a new and unique type of vanadium resource discovered in China. The research of East China University of Science and Technology shows that the graphite concentrate with a fixed carbon content of 73.72% can be obtained by selecting a Jinxi graphite ore by a grinding process for 4 times. The acidification of the flotation graphite concentrate is carried out by acid and alkali methods. Purification can obtain high-purity graphite products with fixed carbon content ≥99.9%; most of the vanadium associated with graphite ore enters the tailings. If the tailings are discarded, it will cause huge waste of vanadium resources. Since vanadium in Jinxi graphite ore is a new type of vanadium resource, vanadium is mainly present in vanadium-doped muscovite in the form of isomorphism, while the structure of vanadium muscovite is very stable, so Jinxi graphite The extraction technology of vanadium in the mine has yet to be studied. From the perspective of protecting resources, the experts have proposed to solve the following problems: 1. The occurrence of vanadium in graphite ore; 2. Separation of vanadium-containing muscovite and graphite; 3. Vanadium white cloud Extraction of vanadium from the mother. As a rare metal with important strategic significance, vanadium is widely used in the fields of aviation industry, atomic energy industry, aerospace industry, and defense industry. It is an indispensable and important resource. Therefore, the research on vanadium extraction technology of Jinxi graphite tailings is of practical significance to promote the development of the graphite ore and improve the guarantee of vanadium resources in China. First, the test plan The only vanadium-bearing graphite ore type currently discovered by Jinxi Graphite Ore, the vanadium extraction technology of this type of vanadium-containing resources is blank in China. Extracting vanadium from stone coal is an important way to obtain vanadium resources, China's stone coal vanadium extraction technology is very mature, vanadium-containing vanadium extraction of graphite tailings laid a good technical foundation. Although the occurrence of vanadium in Jinxi graphite ore is somewhat different from that of stone coal, it has similarities. Based on the achievements of vanadium extraction technology, this experiment explores the vanadium extraction technology of Jinxi graphite tailings. According to the characteristics of vanadium in Jinxi graphite ore, combined with the technology of extracting vanadium from stone coal, the experimental scheme for extracting vanadium from Jinxi graphite tailings was formulated. The principle process flow is shown in the following figure. Figure Jinxi graphite tailings vanadium principle process Second, test raw materials, reagents and equipment Test raw materials: tailings obtained by flotation experiments of Jinxi graphite ore by East China University of Science and Technology. The particle size of the graphite tailings is -0.074 mm, and the chemical composition is shown in Table 1. Table 1 Chemical composition of Jinxi graphite ore flotation tailings ingredient V 2 O 5 Fe 2 O 3 TiO 2 SiO 2 Al 2 O 3 CaO MgO K 2 O Na 2 O Burnout content 0.556 2.23 1.60 79.33 9.89 0.23 4.40 2.56 0.13 1.30 Reagents: concentrated sulfuric acid, analytical grade; kerosene, industrial grade; tributyl phosphate (TBP), technical grade; diisooctyl phosphate (P-204), industrial grade; sodium carbonate, AR; hydrogen peroxide, Analysis Pure; sodium chloride, analytically pure; ammonia, analytically pure; sodium hydroxide, analytically pure. Test equipment and instruments: muffle furnace, SXZ-10-12 type; constant temperature water bath HH-2 type; electric mixer, JJ-1 type; refrigerator, household type. Tested in accordance with Test vanadium GB GB731511-1987, using potassium permanganate oxidation - reduction of ferric ammonium sulfite titration. Third, the test results (1) Adding acid roasting - flooding The vanadium-bearing mineral in Jinxi graphite tailings is vanadium green mica, and v mainly replaces Al in the silicate mineral lattice with the isomorphic form. Vanadium-containing aluminosilicate mineral structure is very stable, difficult to dissolve in water, acids and bases, are soluble refractory material. To leach vanadium in vanadium-containing aluminosilicate minerals, the crystal structure of the aluminosilicate mineral must be destroyed first, and the valence state of vanadium in the aluminosilicate is changed, even if the trivalent or tetravalent vanadium is converted into five. Valence vanadium. Tests have shown that calcination can reduce V 3 + in mica minerals, and V 4 + and V 5 + increase. The test found that the direct oxidization roasting and sodium chloride roasting process, the leaching rate of vanadium is very low. Therefore, the experiment was carried out by changing to the acid roasting process. The results show that the leaching rate of vanadium is much higher than that of direct oxidation roasting and sodium chloride roasting after 500 h of sulfuric acid calcination at 500 °C for 2 h. According to the results of the exploration test, an acid roasting-water immersion condition test was carried out. The test method is as follows: weigh 100 g of graphite tailings sample in mash, add 10 mL of concentrated H 2 SO 4 and appropriate amount of water, mix well, place in a muffle furnace, roast at a certain temperature and time, and then take out natural cooling. . The cooled calcined product was placed in a beaker, 500 mL of water was added, and the mixture was immersed in a constant temperature water bath at 90 ° C for a certain period of time, and vanadium was transferred into the solution in an ionic form, and then the slag was filtered off. Through experiments, the optimum conditions for the determination of graphite tailings by acid roasting-water immersion were as follows: the amount of sulfuric acid added was 10%, the calcination temperature was 550 ° C, the calcination time was 3 h, and the leaching time was 2 h. Under these conditions, the leaching rate of vanadium reaches 95.4% to 95.6%, and the amount of filter residue obtained exceeds 80 g. (2) In addition to potassium in addition to aluminum During the leaching of the calcined product, components such as Al 2 O 3 , Fe 2 O 3 , and K 2 O in the graphite tailings are also dissolved together with vanadium, and enter as K + , Al 3 + , and Fe 3 + ions. In the leachate, the leachate must be purified before the vanadium extraction. The experiment uses condensation crystallization and ammonia hydrolysis to complex potassium and aluminum with potassium alum [K 2 SO 4 ·Al 2 (SO4) 3 ·24H 2 O] and ammonium alum [(NH 4 ) 2 SO 4 ·Al 2 ( The form of SO 4 ) 3 · 24H 2 O] crystallizes (vanadium does not participate in crystallization), achieving the purpose of removing potassium from aluminum. Test method: first concentrate the leachate to the desired concentration, and condense it in a refrigerator at about 5 °C for 24 hours to crystallize potassium and part of the aluminum into potassium alum crystals, and then separate the potassium alum crystals from the leachate. After the potassium alum crystal is separated, a part of Al 3 + is present in the leachate, and a certain amount of ammonia water is added, and an appropriate amount of concentrated sulfuric acid is added to supplement the sulfate ion, so that the remaining Al 3 + is separated by the ammonia ion and the sulfate ion. The ammonium alum crystals are synthesized and separated. According to the test, the optimum conditions for the addition of ammonia water are the volume ratio of the leachate, ammonia water, and concentrated sulfuric acid = 50:7:3.1 (the pH of the solution is about 1). According to the above method, by treating 100 g of graphite tailings, 9.2 g of potassium alum and 23.2 g of ammonium alum can be obtained. (3) Extraction and back extraction Conversion of vanadium in vanadium-containing muscovite to a water-soluble or acid-soluble vanadium-containing ion group by roasting-leaching (eg Test method: the volume ratio of the aqueous phase (leachate) to the organic phase (extractant) = 4:1, adjust the pH of the mixture to between 2 and 3, shake in a separatory funnel, and let stand to make vanadium The aqueous phase is transferred to the organic phase and the residual vanadium content in the raffinate (aqueous phase) is measured. The extract (organic phase) is back-extracted according to the volume ratio of the aqueous phase (regress extracting agent) to the organic phase = 1:4, the vanadium is transferred into the aqueous phase, and then the content of vanadium in the aqueous phase is measured. The test results show that the optimum pH of the extraction-back extraction is 2.6. Under this condition, after three extractions of the leachate, the total extraction rate of vanadium reached 87.6%; after one extraction of the extract, the stripping rate of vanadium reached 99.9%. The vanadium in the stripping solution is tetravalent, and it must be oxidized to the pentavalent state with sodium chlorate before the vanadium is precipitated. After oxidation, the solution was adjusted to pH 1.9-2.2 with ammonia water under stirring, and then stirred at 90-95 ° C for 1 to 3 hours to precipitate ammonium polyvanadate (red vanadium), and the precipitation rate was 99.0%. The test shows that the highest precipitation rate can be obtained by controlling the pH value to about 2; the temperature can accelerate the precipitation of vanadium; the stirring can evenly spread the precipitate and increase the reaction speed, especially when the vanadium concentration in the solution is continuously decreased in the late stage of precipitation, stirring The impact is more obvious. The precipitated red vanadium is washed and then pyrolyzed at 500-550 ° C for 2 h in an oxidizing atmosphere to obtain a brownish yellow or orange-red powdery fine vanadium product. Four or three waste treatment plans In the process of extracting vanadium from graphite tailings, waste gas, waste water and waste slag will be generated. If direct discharge will cause great harm to the environment, it must be treated. Exhaust gas treatment: The exhaust gas is mainly SO 2 gas generated during the addition of graphite tailings to the acid roasting process. In addition, the flue contains a certain amount of soot. For SO 2 gas, natural high specific surface area porous mineral materials can be used for adsorption. For example, clinoptilolite and mordenite have good acid and high temperature resistance, can be used to absorb SO 2 gas, and can recover SO 2 by desorption method. Waste rock treatment: Waste water will be produced during leaching, extraction and vanadium precipitation. It contains acid, organic matter, metal ions, etc. It cannot be directly discharged and must be treated. Direct recycling technology can be used to minimize wastewater discharge. The waste water finally discharged can be treated with a neutralization technique to treat the waste acid, and the organic matter is treated by an activated carbon adsorption process. Metal impurities such as iron, titanium , and magnesium in the wastewater can be precipitated as hydroxides; and a small amount of harmful elements such as chromium ions can be adsorbed by the formed hydroxide. Waste residue treatment: Waste residue mainly refers to the filter residue produced by the graphite tailings after roasting and leaching. The main component of the filter residue is a silicate composed of SiO 2 , Al 2 O 3 , CaO, MgO, K 2 O, Na 2 O, Fe 2 O 3 , TiO 2 , etc., and has a fine particle size (-300 mesh). ), after heat treatment, it has high activity, and can replace it with fly ash and slag as cement admixture and raw materials for building building materials, thereby realizing the recycling of waste residue. V. Conclusion The leaching rate, extraction rate, stripping rate and precipitation rate of vanadium can be 95.5%, respectively, by acid roasting-water immersion-potassium-aluminum-extraction-back extraction-oxide vanadium treatment. 87.6%, 99.9% and 99.0%, at the same time, potassium alum and ammonium alum were obtained at a yield of 9.2% and 23.2%, respectively. In addition, the leaching slag is mainly composed of silicate and has high activity, and can be used as a cement admixture and a raw material for producing building materials.
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After the reaction, the vanadium ion in the leachate is transferred to the organic phase with an organic extractant (85% kerosene + 5% TBP + 10% P-204), thereby separating vanadium from other metal ions (most other metal ions cannot enter the organic phase). phase). The vanadium-containing organic solution was back-extracted with a stripping agent (0.5 mol/L Na 2 CO 3 solution) to transfer vanadium from the organic phase to the rehydration phase.