Leaching, Separation and Enrichment of Low Grade Nickel Copper Ore and Uranium Ore

1. Leaching of low grade nickel-copper ore

(a) ammonia leaching

The reduction roasting-ammonia leaching process used in low-grade nickel oxide ore, also known as the Caron method, was invented by Professor Caron. In the 1950s, the Nicaro smelter in Cuba and the Yabula nickel plant in QNI Australia in the 1970s successively built this production line. The recovery rate of nickel in the whole process is 75%-80%, and the cobalt recovery rate is about 40%-50%. Reduction roasting object is silicic acid to maximize nickel and nickel oxide is reduced to metal, can be rotary kiln, multiple hearth furnace or a fluidized bed furnace, the degree of reduction is generally controlled at 60% -70%, the average residence time of about 0.5h, while controlling the reduction conditions, most of the Fe ^{3+ is} reduced to Fe ₃ O ₄ , only a small part of Fe ³⁺ is reduced to metal, combined nickel oxide (such as NiO·SiO ₂ , NiO·Fe ₂ O ₃ ) Reduced to a live, free metallic nickel. The so-called ammonia leaching is to use a multi-stage countercurrent leaching method under normal pressure to reduce nickel and cobalt in the calcined calcined sand by Ni(NH ₃ ) ₆ ²⁺ and Co(NH ₃ ) ₆ ^{2+ .} The form is transferred to the solution, and iron , magnesium, etc. are present in the slag, thereby achieving preliminary separation of nickel, cobalt and iron. The biggest disadvantage of ammonia leaching is that the recovery of cobalt is not high, less than 60%.

Low-grade copper oxide ore leaching ammonia can also take measures, gangue overbased copper oxide as copper oxide Yunnan DONGCHUAN Tangdan treatment, 0.8% -1.5% copper, mine schist, good weathering carbonate The salt content is high, and the content of alkaline gangue (CaO+MgO) in minerals is more than 10%. If the acid leaching process is adopted, not only the acid consumption is large, but also economically unreasonable; at the same time, the formation of a large amount of calcium sulfate during acid leaching tends to cause the pile to be kneaded, which is not conducive to the penetration of the solution. The plant is the first copper plant in China to adopt a low-concentration ammonia immersion heap leaching method. The overall process is designed by the Beijing Research Institute of Mining and Metallurgy and has a design capacity of 300-500 tons of cathode copper per year. The ore is open-pit mining and is crushed by a jaw crusher. After crushing, the particle size is about 50mm, and the piles are piled up. The height of each layer is 6m. The heap is laid by drip irrigation net drip irrigation and leaching, while inhibiting the evaporation of ammonia. The leachate contains copper 1-1.5g/L, and the copper is extracted and extracted by steam floatation to return to the immersion heap. The extraction system is a two-stage extraction, a first-stage washing, and a first-stage stripping operation. The main reagent liquid ammonia consumption is about 1.5 t NH ₃ /tCu.

(2) Acid leaching

The high-pressure acid leaching process began in the late 1950s, and the core of the process technology included autoclave technology and solution processing technology. Compared with the reduction roasting-ammonia leaching process, the high-pressure acid leaching process has the advantages of low energy consumption, high nickel recovery rate, and high cobalt leaching rate (up to 90% or more). High-pressure acid leaching of low-grade nickel oxide ore is usually carried out by selectively leaching nickel and diamond with sulfuric acid, including three steps of slurry preparation, leaching and nickel-cobalt recovery. The ore is washed and sieved, and water is added to make a slurry with a solid content of 25%, and the thickener is dense. The solids in the underflow account for 45% to 75% and are pumped to the leaching section. Under the high temperature and high pressure conditions of 250-270 ° C and 4-5MP, nickel, diamond and the like are dissolved together with iron and aluminum minerals with dilute sulfuric acid, and a certain pH value is controlled to make a small amount of iron, aluminum and silicon leached. The impurity element is hydrolyzed into the slag, and nickel and cobalt selectively enter the solution. The leachate is neutralized and precipitated with hydrogen sulfide to obtain high-quality nickel-cobalt sulfide, and the final product is produced by a conventional refining process. The three nickel plants in Cawse, Bulong and Murrin Murrin in Western Australia use high-pressure acid leaching to treat low-grade nickel oxide ore. The annual production capacity of the first phase is 2.7-30,000 tons. The total investment is A$2.16 billion. The biggest advantage of high-pressure acid leaching is that the leaching rate of cobalt is high, up to 90%, which is much higher than other processes. However, the high-pressure acid leaching method is only suitable for the treatment of oxidized ore with low magnesium content, because high magnesium content will increase the acid consumption and affect the subsequent process. In addition, since the leaching solution is always in a supersaturated state during the high-pressure acid leaching process, solid precipitates are continuously formed in the solution, and most of the precipitates form leaching slag, and a small part forms scale inside the autoclave, which affects the operation of the high-pressure acid leaching process. High-pressure acid leaching requires high-pressure conditions, which have high requirements on equipment, scale, investment, operation control, etc., and also affect its promotion and application. Therefore, if it can be operated under normal pressure conditions, it will revolutionize the treatment technology of oxidized ore.

The general process for treating nickel oxide ore by atmospheric pressure acid leaching is as follows: grinding or classifying the ore first, adding the ground slurry to 10% dilute sulfuric acid solution, leaching temperature of about 90 ° C, stirring under normal pressure, ore The nickel leaching into the solution, the nickel leaching rate can reach 80%, and the cobalt leaching rate can reach more than 60%. The leachate is further neutralized with calcium carbonate, filtered and subjected to liquid-solid separation, and the obtained leachate is subjected to nickel precipitation using CaO or Na ₂ S as a precipitating agent. European Nickel is currently conducting large-scale heap leaching tests on nickel oxide ore in Turkey and is expected to build the world's first plant to extract nickel and cobalt using heap leaching technology. The disadvantage of the atmospheric pressure acid leaching method is that the heap is easy to be knotted, the solution permeability is poor, and the leaching effect is affected; the Fe ³⁺ and Al ³⁺ are leached in a large amount, the leaching slag is large, and the acid consumption is high; in addition, the iron removal is all common. The problem that the pressure acid leaching process must face.

The successful case of atmospheric pressure acid leaching for low-grade copper oxide ore is the Zhongtiaoshan copper mine, which is the first in China to use the underground leaching technology to treat refractory low-grade copper oxide ore. Designed by the Institute and Changsha Mining Research Institute, the design capacity is 500tCu/a, which was put into operation in May 1999. Underground leaching technology is a kind of mineral processing technology combining mining, selection and smelting. It does not need to mine ore, does not destroy vegetation and ecology, and has no pollution to the environment. For those with low grade, deep burial, unsuitable mining or engineering geology In complex conditions, ore bodies that cannot be mined or uneconomical using conventional techniques are important. The Zhongtiaoshan Copper Mine Copper Mine has more than 4 million tons of low-grade copper oxide ore in the gob of 930m elevation. The average grade of ore is 0.6% and the oxidation rate is over 50%. Using underground leaching technology, the solution is collected in the old mine tunnel by spraying on the surface and pumped to the surface for extraction. The leachate contains 1~3g/L of copper, and adopts two-stage extraction and one-stage stripping operation. Another example is the San Manuel copper mine in Arizona, USA. It is a large porphyry copper mine. It began mining in the 1950s. The upper oxidized ore was heap leached and the lower goaf was used for underground leaching. The annual production capacity was 7.3×10 ⁵ tCu.

(3) Bioleaching

The industrialization of bioleaching technology began in the 1960s with copper and uranium mines. By the 1980s, bioleaching technology developed more rapidly, and it was used in large-scale industrial applications in metallurgy such as copper, uranium and gold. Research and application of bioleaching The field has been expanded from the extraction of copper, uranium, gold, etc. to nickel, cobalt, zinc , molybdenum , phosphorus , coal desulfurization and other fields. By 1999, the biological extraction of nickel-cobalt ore has also achieved industrial applications, marking the nickel-cobalt mine. Bioleaching has moved from the laboratory to industrial applications. Since the 1980s, some domestic research units such as the Beijing Research Institute of Nonferrous Metals, the Institute of Process Engineering of the Chinese Academy of Sciences, and Central South University have systematically studied the bacterial leaching mechanism of various metal ores to select for pH and A bacteria with good temperature tolerance, high toxicity and high leaching efficiency.

For the low-grade nickel-copper mines in the Jinchuan No. 1 Mine (Longshou Mine) and the No. 2 Mining Area (including lean ore, off-balance mines, mixed ore and tailings produced by the current beneficiation process), Fang Zhaojun and others used the oxidation provided by the Institute of Microbiology of the Chinese Academy of Sciences. The leaching experiments were carried out by Thiobacillus ferrooxidans (Tf) and Thiobacillus thiooxidans (Tt). Under the optimized conditions of leaching time of 10d and temperature of 35 °C, the nickel leaching rate could reach 80%, copper reached 45%, and cobalt reached 78%.

Bacterial leaching of oxidized ore is the use of the oxidative or reducing properties of the microorganism itself to redox certain components of the mineral to separate from the original mineral. There are few bacteria that can be used for leaching of nickel oxide ore. The most studied bacteria are Aspergillus niger.

In general, bioleaching is a very effective means for resource management of tailings and lean ore. However, the defects that are difficult to overcome in bioleaching are low metal leaching rate, long leaching period, poor adaptability of bacteria to the environment, and leaching temperatures. Obviously, in hot and humid areas, evaporation of water is also a problem that needs to be leached.

2. Separation, enrichment and recovery of nickel and copper in leachate

(1) Chemical precipitation method

Ni and Cu in the leachate can be precipitated in the form of sulfide by using sodium sulfide, and the Ni and Cu sulfides can be subjected to pressure oxidative leaching or pyrometallurgical smelting, but Fe will also precipitate at the same time during the precipitation, and the addition of sodium sulfide is made. H ₂ S gas is inevitably produced in the production process, and a corresponding exhaust gas absorbing device is required for this purpose, which increases safety difficulty and investment. Adding alkali precipitation will precipitate components such as Ni, Cu, Fe, Mg, etc. Because of the high MgO content, it is usually about 15%, which is not conducive to furnace smelting. After reducing the MgO treatment, it takes a long process to realize it into nickel-copper products.

(2) Organic extraction method

The organic extractant containing elements such as N, P, S, O, etc. can be used to separate and enrich the metal components such as Ni and Cu in the leachate. The organic extractant includes: tertiary amines, carboxylic acids, organic phosphoric acids, and organophosphines. An acid, an organic phosphinic acid, an organic thiophosphinic acid, a ketoxime or an aldoxime. Chen Ailiang et al. used a copper chloride bioleaching solution with Lix984 (a mixture of Lix860 (aldoxime) and Lix62 (ketooxime) in a high flash point kerosene with a volume ratio of 1:1.) The results showed that the pH value was greater than 2.22. Compared with O/A=1:1, the stirring speed is 200r/min, the stirring time is 4min, the extraction grade is 3, the extraction rate of copper can reach above 99.8%, the copper distribution ratio can reach more than 600, the iron distribution ratio Less than 1, the separation coefficient of copper and iron can reach 1900 or more. Wang Shengdong et al. used Lix84 to extract and separate nickel, cobalt and copper from ammonia solution. Firstly, the copper and nickel were co-extracted in a 5-stage countercurrent, and the cobalt remained in the raffinate. The loading phase containing copper and nickel is washed away by ammonia in a second-stage washing, and the nickel electrolysis waste liquid is used for 7-stage countercurrent selective stripping of nickel to realize preliminary separation of nickel and copper; then, copper is extracted from the copper-containing supporting phase to obtain pure Copper sulfate, nickel solution obtained by stripping nickel is still extracted by Lix84 to extract copper and recover copper, thereby completely separating copper and nickel to obtain pure nickel sulfate solution, so that nickel-cobalt copper in the leachate is completely separated.

The organic extraction method has been widely used in wet smelting of nickel and copper, but there are also obvious defects: multi-stage serial extraction and stripping process are required to achieve certain separation efficiency and complicated operation; extractant and diluent are easy Evaporation is volatile, which brings safety hazards to production; entrainment and loss of extractant can cause environmental pollution; extractant and thinner remaining in the stripping solution will affect the electrowinning process and the final quality of nickel and copper products. .

(3) Resin adsorption method

The ion exchange resin generally used for adsorbing and separating metal ions has a cation exchange resin and a chelating resin. The adsorption force of the former is mainly electrostatic attraction, and the adsorption force of the latter is mainly chemical chelate coordination. Since the cation exchange resin uses electrostatic attraction as the main adsorption driving force, it preferentially adsorbs high-valent ions. Specifically, the order of adsorption of some metal ions by the cation exchange resin is: Th ⁴⁺ >Fe ³⁺ >Al ³⁺ >Cu ²⁺ >Ni ²⁺ >Mg ²⁺ >K ⁺ >Na ⁺ . Since nickel and copper tailings are usually accompanied by iron, it is obvious that ordinary cation exchange resins are not suitable for the enrichment and separation of nickel and copper. The chelating resin is an organic chelating group containing an element such as N, P, S, O or the like on the resin skeleton, and elements such as N, P, S, O and the like in the organic chelating group may be combined with a specific metal ion. A chemical coordination occurs to form a stable multi-ring structure inside the resin, thereby separating the metal ions from the solution. Therefore, if a highly selective chelating resin can be developed, various disadvantages of the organic extracting agent can be overcome, and resource management of tailings and lean ore can be realized.

Since the ion exchange resin usually preferentially adsorbs high-valent ions, the high-valent Fe ³⁺ will be selectively adsorbed at the same concentration, not to mention the Fe ³⁺ concentration in the oxidized ore leaching solution is much higher than the Ni ²⁺ and Cu ²⁺ concentrations, and Also subject to a lot of interference from Mg ²⁺ . Therefore, the development of ion exchange resins with strong Cu/Ni selectivity and large adsorption capacity has become a key technical issue for low-grade nickel and copper ore wet smelting.

3. Wet smelting of uranium ore

Human energy utilization has experienced the evolution of low-carbon and carbon-free energy from fossil energy and nuclear energy, nuclear energy, hydropower, wind energy, solar energy, biomass energy, etc. from fossil firewood to coal age, oil and gas era and now to coal and oil. As the total energy use continues to grow, the energy mix is ​​constantly changing. Every change in the energy age is accompanied by a huge leap in productivity, which has greatly promoted the development of human economy and society. At the same time, with the increasing use of energy, especially fossil energy, the constraints of energy on human economic and social development and the impact on resources and environment are becoming more and more obvious.

At present, fossil energy is still the main body of human energy consumption. According to statistics, in 2006, the world's total commodity energy consumption accounted for 35.8% of oil , ranking first; coal accounted for 28.4%, ranking second; natural gas accounted for 23.7%, ranking third; fourth place was hydropower, Accounting for 6.3%; nuclear energy used in the form of electricity accounted for 5.8% of the world's primary commodity energy consumption, ranking fifth, of which nuclear power accounted for 14.8% of the world's total electricity consumption. Among them, oil, coal and natural gas are non-renewable fossil energy sources, and there will always be a day of exhaustion in the long run. Moreover, the production and use of oil and natural gas will cause a large amount of greenhouse gas emissions such as CO ₂ and CH ₄ ; in addition to discharging a large amount of CO ₂ , coal also emits SO ₂ , soot, dust and nitrogen oxides. Wait for atmospheric pollutants. These emissions are recognized as the main cause of global warming and climate anomalies, as well as environmental problems such as acid rain and acidification of soils, rivers and lakes. Therefore, countries regard low-carbon and carbon-free energy such as nuclear energy, hydro energy, wind energy, solar energy and biomass energy as the focus of future development. From the first World Climate Conference in 1979 calling for the protection of the climate system, to the adoption of the United Nations Framework Convention on Climate Change by the United Nations Conference on Environment and Development in 1992, and the introduction of the Kyoto Protocol, the international community has made a response to global climate change. continue trying. As the international community pays more and more attention to environmental issues and the continuous advancement of energy technology, the share of coal, oil and natural gas in total primary energy demand will further decline, and the share of clean energy such as nuclear, wind, solar and biomass will continue to increase. .

Nuclear power does not emit SO ₂ , soot, dust, nitrogen oxides, etc., and the normalized emissions of nuclear power chains in greenhouse gas emissions are only equal to 1% of the coal-fired chains. The State Council has formulated a policy of vigorously promoting the development of nuclear power, and proposed a medium- and long-term development plan for nuclear power. It is clear that China's nuclear power installed capacity should reach 40 GW or more in 2020 (at that time, it will account for 4% of the country's total installed capacity, and its proportion is still higher than the current world. The developed countries that use nuclear power are much lower and lower than the world average. To achieve this goal, it is necessary to start construction of about 30 million kilowatt-class nuclear power units in the next 10 years, and it is required to start construction every year from now on. 3 million kilowatt-class nuclear power units.

Since the technical controllable nuclear fusion is technically difficult, the utilization of nuclear power will be dominated by nuclear fission energy for a long period of time in the future. Nuclei produced by the nuclear fission neutron bombardment of uranium-233 only fissile material, uranium-235, plutonium-239 three kinds, uranium-233 and plutonium-239 which does not exist in nature, they are a natural thorium -232 and uranium-238 absorb (capture) neutrons after decay production, the only fissile material present in nature is uranium-235. The current nuclear industry system is basically based on the uranium-235 thermal neutron fission. To achieve the goal of China's nuclear power installed capacity of 40 GW in 2020, it is necessary to improve and guarantee China's nuclear fuel cycle system, including uranium exploration and mining, uranium water smelting plant (uranium extraction and purification), uranium conversion plant , uranium enrichment plants, fuel rod manufacturing plants, heavy water plants, light water reactors (power stations), heavy water reactors (power stations) and spent fuel rod treatment plants. In the nuclear fuel cycle system, the first thing to do is to do the uranium exploration and mining and the extraction and purification of uranium.

According to the statistics of the uranium geology system in 1989, the uranium ore grade of China's deposits is mostly between 0.1% and 0.3%, and the average grade of the deposit is 0.115%. The geological grade of about half of the country's deposits is between 0.1% and 0.2%. The average grade of the deposit is more than 0.3%, which is only 6% of the total deposit. The average grade of the deposit is less than 0.1%, accounting for about 33% of the total deposit.

In order to extract uranium, the uranium is usually transferred from the ore to the solution by means of a wet smelting process, that is, uranium smelting. The process is acid leaching and alkali leaching. Regardless of the leaching method, anions of uranium are formed in the leachate, such as acid leaching solution using sulfuric acid as the leaching agent. Uranium is generally [UO ₂ (SO ₄ ) ₂ ] ^2- and [UO ₂ (SO ₄ ) ₃ ] ^4- Anionic form is present, and uranium is usually present as [UO ₂ (CO ₃ ) ₃ ] ^4- complex anion in an alkali leaching solution using a sodium carbonate or sodium carbonate-sodium bicarbonate mixed solution as a leaching agent.

The concentration of uranium in the uranium ore leaching solution is still very low, and it also contains a large amount of impurities. The uranium needs to be extracted and concentrated to prepare a relatively pure uranium compound, and then further purified to remove impurities to obtain a nuclear-grade pure uranium compound. There are two main methods for the extraction of uranium: solvent extraction for pulp or leachate with high uranium concentration and ion exchange for low uranium concentrations. Organic extraction agents such as tributyl phosphate and tri-fatty amine are commonly used in the extraction method. The biggest problem of the extraction method is the secondary pollution of the organic matter in the industrial water environment, followed by the complicated process.

Because the grade of uranium ore in China is generally not high, the extraction process of uranium in the leachate is more by ion exchange. At present, a strong basic anion exchange resin with polystyrene-divinylbenzene as a skeleton is commonly used to adsorb uranium in the leachate. For example, the exchange process of [UO ₂ (SO ₄ ) ₂ ] ^2- and [UO ₂ (SO ₄ ) ₃ ] ^4- anions in the ion exchange resin with the acid leaching solution is as follows:

2R ₄ NX + [UO ₂ (SO ₄ ) ₂ ] ^2- → (R ₄ N) ₂ UO ₂ (SO ₄ ) ₂ + 2X ^-

4R ₄ NX + [UO ₂ (SO ₄ ) ₃ ] ^4- → (R ₄ N) ₄ UO ₂ (SO ₄ ) ₃ + 4X ^-

However, the current strong alkaline anion exchange resin, such as the domestic brand of 201×7 (product performance equivalent to Amberlite IRA-400 in the United States, Diaion SA-10A in Japan, Lewatit M500 in Germany and Allassion AG217 in France) has a treatment of uranium ore leachate. Obvious disadvantages: 1) The adsorption capacity is small, the total exchange capacity of the wet resin to the monovalent anion is about 1.0 mmol/ml, and the working exchange capacity is less than 0.4 mmol/ml, [UO ₂ (SO ₄ ) ₂ ] ^2- and [UO ₂ (SO ₄ ) ₃ ] ^4- is a divalent and a tetravalent, respectively, and thus the adsorption capacity of the resin is smaller, which is equivalent to only 1/2 and 1/4 of the monovalent ion. Hu Kaiguang et al. used a adsorption column with a diameter of 100 mm×7350 mm and a resin loading of about 26 L. The adsorption performance of 201×7 strong basic anion resin on uranium was studied under the adsorption flow rate of 30-40 m/h. The saturated adsorption capacity is only 0.05 mmol/ml (11.9 mg/ml), and the uranium concentration in the adsorption tail liquid is about 0.1 mg/L. 2) The transformation expansion rate is more than 30%. In actual operation, it is necessary to reserve a certain space in the adsorption tower, so that the adsorption is not thorough enough, resulting in a high residual adsorbate concentration in the adsorption tail liquid. 3) The resin skeleton is an organic skeleton, which is not resistant to radiation. The long-term high-intensity radiation in the uranium extraction process, coupled with repeated expansion-contraction during resin transformation, easily causes the resin to be broken.

Fourth, research progress in ion exchange resins

The science of ion exchange technology has gone through more than one hundred years of development. In 1850, two British agricultural chemists H. S. Thompson and J. T. Way discovered the phenomenon of ion exchange in the soil; in 1905 the German chemist R. Gans uses artificial zeolite to soften hard water and purify sugar juice; in 1933, British B. A. Admas and E. L. Holms synthesized a phenolic type of anion-cation exchange resin; 1945 American G. F. D. Alelio invented a more excellent styrene-based and acrylate-based ion exchange resin, and the application technology for chemical desalination to prepare pure water has been rapidly developed. On this basis, scientists from various countries have developed ion exchange resins for different uses such as amphoteric, chelated, redox and other polymers based on polystyrene and acrylate polymers. Up to now, ion exchange technology has penetrated into various fields of the national economy such as industry and agriculture, medical and health research, and has been widely used.

In terms of metal smelting, in the 1950s, Peru first used ion exchange technology for wet copper smelting. Metallurgists in the former Soviet Union also did a lot of research in this area. In the 1990s, RSA Laboratories of the United States extracted metal platinum and other rare metals with Superlig resin at Impala Platinum Co., Ltd. However, in the field of wet smelting, organic extractants are used to separate and enrich metal components. The main reason why ion exchange technology cannot be applied to wet smelting on a large scale is that the ion exchange resins used in the world are absolutely large. Most of the organic ion exchange resins based on styrene or acrylic polymers have insurmountable defects: slow exchange rate, short service life, high product moisture content, and periodic expansion-contraction during adsorption-regeneration. Such drawbacks, especially its poor adsorption selectivity, make it difficult to obtain industrial applications by separating and enriching valuable metals in acid leaching liquids with very complex compositions.

In addition, when using an organic resin having a high water content in an alpine region such as Jinchuan, attention should be paid to antifreeze. Otherwise, the resin may be broken due to volume expansion of water in the pores, which may cause the resin to be broken, thereby reducing the mechanical strength and service life of the resin. Also, repeated expansion-contraction causes the resin to be subjected to repeated internal stresses, causing fatigue of the resin structure, resulting in cracking, pulverization, and loss of the resin; because the expanded expansion resin needs to reserve a certain empty volume when packing the column, and cannot be filled. Otherwise, the resin column may burst when the transformation expands. According to the test results, when the strong acid cation exchange resin is changed from Na ⁺ type to H ⁺ type, the volume will expand by about 10%; when the strong basic anion exchange resin is changed from Cl ^- type to OH type, the volume will expand by about 30%. When the weakly acidic cation exchange resin is changed from H ⁺ type to Na ⁺ type, the volume can be expanded by more than 50%; when the weakly basic anion exchange resin is changed from OH ^- type to Cl ^- type, the volume can be expanded by more than 20%. Therefore, how to obtain an ion exchange resin with high adsorption selectivity and excellent adsorption performance has become a key technical problem for solving the smelting of Jinchuan low-grade ore.

The inorganic ion exchange resin engineering technology research center of Henan University uses the inorganic material-silica gel as the skeleton to produce the SI series inorganic ion exchange resin, which solves the problems of organic resin in the wet smelting application. The research results of inorganic ion exchange resins which have been industrialized include: 1. SICu and SI-1 with high adsorption capacity and exchange rate for transition metal ions such as Cu ²⁺ , Ni ²⁺ , Zn ²⁺ and Co ²⁺ . , SI-2, SIB-1, SIB-2 type ion exchange resin; Second, SI-3, SIB-3 type ion exchange with specific adsorption selectivity for heavy metal ions such as Pb ²⁺ , Cd ²⁺ , Hg ²⁺ Resin; 3. SIAP-type ion exchange resin which can be used to remove trace Fe ³⁺ ions contained in Cu ²⁺ /Ni ²⁺ /Zn ²⁺ /Co ²⁺ plasma; Fourth, it can be used for wastewater treatment or seawater desalination removal B (OH) ^{4 -} SIB-4 anion type ion-exchange resin; 5, using the existing fixed carrier resin was used to remove water _{^{HAsO 4 2-, H 2 AsO 4-}} , SeO 4 2-, HSeO 3 ^- Technology of highly toxic anions such as CrO ₄ ^{2 -} and CN ^- .

As a series of products, inorganic ion exchange resins have unique advantages over traditional styrenic and acrylic organic ion exchange resins: (1) organically polymerized with hydrophobic styrene and acrylic In terms of the skeleton of the material, the silica gel/polymer composite has strong hydrophilicity and large grafting density of functional groups, and the series of inorganic ion exchange resins thus obtained exchanges metal ions faster in an aqueous solution. More thorough, especially for the removal of trace heavy metal ions in aqueous solutions. (2) Unlike the organic polymer skeleton ion exchange resin, periodic expansion-contraction occurs during use, so the service life is greatly improved, and the number of cycles of use is 10 times higher than that of the organic polymer skeleton ion exchange resin. (3) The chemical bond of the silica gel skeleton is mainly silicon-oxygen bond (Si-O), and the bond energy is 422.5 KJ/mol, which is much higher than the carbon-carbon bond (CC bond energy of 347 KJ/mol) in the organic skeleton ion exchange resin. Even high temperature, ultraviolet or radiation irradiation, strong oxidizing agents do not easily cause silicon-oxygen bond rupture or decomposition, and have thermal stability, radiation resistance, oxidation resistance and mechanical physical properties unmatched by organic polymer materials. (5) Using silica gel as the skeleton material, it does not depend on petroleum, and the source is wide and cheap. It can save a lot of non-renewable petrochemical resources, which is economical and environmentally friendly, and conforms to the development idea of ​​national green manufacturing.

5. Inorganic ion exchange resin enriches and purifies copper, nickel and uranium

SI Series inorganic type ion exchange resin SICu resin (silica gel pyridine skeleton high selective copper chelating resin) can be selectively adsorbed at a high concentration of Cu ²⁺ Fe, Al ^3+, Ca ^2+, and Mg ²⁺ where The exchange capacity is about 0.5mmol/ml in the pure Cu ²⁺ system and not less than 0.35mmol/ml in the complex ionic system; the SI-2 resin (the amine carboxyl chelating nickel specific selective resin of the silica gel skeleton) can be Selective adsorption of Ni ²⁺ at high concentrations of Fe, Al ³⁺ , Ca ²⁺ and Mg ²⁺ with an exchange capacity of approximately 0.35 mmol/ml in a pure Ni ²⁺ system and not less than 0.3 in a complex ionic system Mmmol/ml. After strict performance testing, the exchange capacity of SICu and SI-2 resin decreased by less than 10% after repeated use for 5000 times. Thus, SICu and SI-2 resins are particularly suitable for wet smelting of low grade nickel-copper ore.

The functional group contained in SI-l or BP-1 resin is an amine group, which is a weakly basic anion resin with a working exchange capacity of 1.0 mmol/ml or more. It is also very suitable for use in uranium hydrometallurgical plants in terms of chemical structure. Extraction and separation of uranium anions. In addition, after the uranium compound is extracted, it must be purified. Because uranium ore leaching solution often contains metal elements such as calcium (Ca), magnesium (Mg), aluminum (Al), and iron (Fe), cadmium (Cd), molybdenum (Mo), tungsten (W), and chromium (Cr). , rare earth elements such as vanadium (V), and non-metallic elements such as boron (B). The cation formed by the metal and the rare earth is not adsorbed by the anion exchange resin, but since boron and cadmium have a strong ability to absorb neutrons, it is called a high neutron absorption cross-section element or a neutron poison, even if it is present in a nuclear fuel. The chain fission reaction cannot be maintained. The purpose of the extracted uranium compound is to remove possible neutron poisons and obtain nuclear-purified uranium products. Among them, boron may form B(OH) ^{4 -} anion in uranium ore leachate, which is easily adsorbed by anion exchange resin and mixed into uranium extract. B(OH) ^{4 -} can be removed by boron selective adsorption resin SIB-4. The performance is up to 2mmol/g, and the adsorption capacity is four times that of the commercial boron resin Amberlite IRA-743 (the adsorption capacity is about 0.5mmol/g) of Rohm & Hass. The removal of trace amounts of cadmium ions can be achieved by using a thiol-chelating type of SI-3 or SIB-3 resin, which can reduce the cadmium ion concentration to below 0.5 ppb.

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More Production in Less Time – Multitudes of affordable CNC Routers are available that can reduce the production time substantially while increasing the precision. Buy CNC Router to increase the production rate and profits.
Reduce the Training Time – Acquiring expertise over CNC Routers is very easy. A rookie can become a pro in no time. Be it a 3-Axis CNC Router or any other, as the operator operates the machine through a computer-guided interface, gaining expertise becomes very easy.
Decrease Injury Risk – If you purchase CNC Router, the probability of work-related injury goes down significantly since the operator actions are aided by the computer interface and it comes with additional injury prevention measures.

Cnc Router Series

Cnc Router,Router Machine,Cnc Router Machine,Desktop Cnc Router

Shandong U-May CNC Technology Co., Ltd. , https://www.fiberlasers.de