China Metallurgical Encyclopedia: Non-ferrous Metal Metallurgy

Author: Chief Editor: Liu Jin
Publisher:
Publishing Date: 1999-01-01
Features:
Segment: The solvent extraction enrichment separation process is entirely liquid-phase operation, without the toxicity caused by thallium volatilization, and provides good working conditions with a short process flow. The recovery rate of thallium from the enriched thallium slag leach solution to the thallium ingot is 97%, and from the enriched thallium ash to the thallium ingot is 84%, an increase of 28% and 26% respectively compared to the original precipitation method (baghouse dust leached with water, potassium permanganate oxidation, and alkali neutralization to obtain neutral slag, followed by chlorination precipitation, sulfation roasting, soda neutralization, and zinc plate replacement) and the sulfide-precipitation-exchange method (sulfation roasting of enriched thallium ash, water leaching, chlorination precipitation, and sodium sulfide treatment, followed by sulfation roasting leaching, hydrogen sulfide impurity removal, and zinc replacement for thallium). The production cost is also significantly reduced. The A101 solvent extraction process for thallium is the first solvent extraction method applied in Chinese thallium production and one of the earlier industrialized extraction processes in the world's thallium extraction metallurgy development history. Due to the need for users to synthesize A101 themselves, it was gradually replaced by the commercial N503 (N,N′-dimethyl) with very similar structure and performance in later thallium production.
References: Ma Rongjun, Application of Solvent Extraction in Hydrometallurgy, Metallurgical Industry Press, Beijing, 1979. (Zhong Xiang)
Actinium (Ac) is a radioactive metal. Its element symbol is Ac, atomic number is 89, and the relative atomic mass of the element is 227.0278. It belongs to the actinide series. In 1899, Frenchman A.L. Debierne discovered and isolated actinium from uranium tailings. Its name comes from the Greek word aktinos (ray). Twenty-five isotopes of actinium with mass numbers ranging from 209 to 233 have been discovered. Except for 227Ac and 228Ac, which are natural radioactive elements, the rest are synthesized through artificial nuclear reactions. 227Ac is the most important actinide isotope. It is a member of the actinium-uranium radioactive decay series, with a half-life of 21.773 years. In uranium ores that have reached radioactive equilibrium, the mass ratio of 227Ac to uranium is 2×10?1?:1. Actinium is a silver-white metal with a melting point of 1320K ± 50K and a boiling point of 3470K ± 300K. Its density (at 293K) is 10062 kg/m3. The metal actinium has a face-centered cubic lattice. The outer electron configuration of actinium atoms is (Rn) 6d1?s2. The oxidation state of actinium is +3. Its chemical properties are very similar to those of lanthanum and yttrium. The fluorides, hydroxides, carbonates, phosphates, and oxalates of actinium are insoluble in water. Trace amounts of actinium are commonly carried by co-precipitation with lanthanum fluoride or lanthanum oxalate. Ion exchange chromatography (see rare earth element chromatography separation) or solvent extraction methods can be used to separate actinium from lanthanide elements. Since uranium ores contain rare earth elements, only a concentrate of actinium can be obtained from uranium ores. In a reactor, irradiating radium-226 targets with thermal neutrons can produce high-purity 227Ac through nuclear reactions. Dissolving the irradiated radium targets with dilute nitric acid, adding concentrated nitric acid to precipitate radium, filtering, and passing the filtrate through an anion exchange resin column can separate 227Ac from thorium-228. Then, the oxalate precipitation method is used to purify actinium, and it is calcined at 973K to obtain Ac?O?. Belgium produced about 20g of actinium-227 using this method in the 1970s.
References: J.J. Katz et al., The Chemistry of the Actinide Elements, Vol. I, Chapman and Hall, London, 1986. (Cen Yunhua)
Transactinide elements are elements with atomic numbers greater than 103, also known as superactinides. Elements that have been synthesized include element 104, element 105, element 106, element 107, element 108, and element 109. According to nuclear theory and the periodic table, scientists predict that chemical elements with atomic numbers greater than 110 may exist. Between atomic numbers 121 and 152, there will be a transition element series similar to the actinide series, known as superactinides. (Cen Yunhua)
Actinide elements are the 15 radioactive elements in the 7th period, 3B group of the periodic table, including actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, and lawrencium. Their atomic numbers range from 89 to 103. The first four are naturally occurring, while the remaining 11 are produced through artificial nuclear reactions. Alpha decay and spontaneous fission are common nuclear properties of actinide elements. The outer electron configurations of actinide element atoms are similar to those of lanthanide elements, and their chemical properties are also very similar to those of lanthanide elements. As the atomic number increases, the ionic radius of actinide elements decreases, a phenomenon known as ionic radius contraction. The most common oxidation state of actinide elements in aqueous solutions is +3, but protactinium has a +5 oxidation state, while uranium, neptunium, and americium have both +5 and +6 oxidation states. Neptunium and plutonium have a +7 oxidation state, while uranium, thorium, and plutonium have a +4 oxidation state. Elements such as californium, einsteinium, fermium, mendelevium, and nobelium have a +2 oxidation state. The hydroxides, fluorides, carbonates, and oxalates of actinide elements are insoluble in water, while their nitrates, sulfates, perchlorates, and halides are soluble in water. The annual production volume of actinide elements: uranium is in the ten-thousand-ton range; thorium is in the hundred-ton range; plutonium is in the ton range; neptunium, americium, and curium are in the kilogram range; actinium, protactinium, and californium are in the gram range; berkelium is in the hundred-milligram range; einsteinium is in the milligram range, and the rest are in trace amounts. The applications of actinide elements are becoming increasingly widespread. Uranium-233, uranium-235, and plutonium-239 are used as fuel for nuclear reactors and nuclear power plants, while actinium-227, curium-244, and plutonium-238 are used as heat sources for spacecraft.
References: J.J. Katz et al., The Chemistry of the Actinide Elements, Vol. I, Chapman and Hall, London, 1986. (Cen Yunhua)
Einsteinium (Es) is an artificial element with the element symbol Es and atomic number 99. It belongs to the actinide series. The isotope with the longest half-life is 254Es. In 1952, American G.R. Choppin and others discovered element 99 in the products of a thermonuclear explosion. To honor the famous physicist Albert Einstein, the new element was named Einsteinium. Einsteinium has 12 isotopes with mass numbers ranging from 245 to 256 and half-lives from 20 seconds to 400 days. 253Es and 254Es are important isotopes of einsteinium. Einsteinium is a silver-white metal with a melting point of 1130K ± 30K and a density (at 293K) of 13700 kg/m3. The outer electron configuration of einsteinium atoms is [Rn] 5f117s2. During the thermonuclear explosion process, uranium-238 absorbs neutrons multiple times, undergoes β decay to form 253Es. The nuclear reaction is: 23?U + 1?n → 2?3U?β → 2?3Es. In 1961, measurable amounts of einsteinium were isolated from plutonium irradiated with high-flux neutrons for three years in a reactor. Neutron irradiation of 253Es can produce 254Es and 255Es. (Zhang Wenqing)
Reduction smelting of copper in low-shaft blast furnace (reduction smelting of copper in low-shaft blast furnace) is a copper smelting method that produces black copper by treating copper matte obtained from sulfide copper concentrate through dead roasting in a low-shaft blast furnace. This method has certain requirements for the chemical composition of the copper concentrate, specifically a copper content of 15%–45%, an iron content of 15%–40%, and a sulfur content of 20%–45%, with the sum of these three components exceeding 85%. It mainly includes three stages: dead roasting of sulfide copper concentrate, hot pressing of matte, and reduction smelting in a low-shaft blast furnace. Dead roasting of sulfide copper concentrate is carried out in a fluidized bed roaster, with a roasting temperature of 1133–1173K, achieving a desulfurization rate exceeding 96%. During the roasting process, the copper in the sulfide copper concentrate is oxidized to copper oxides, and most of the iron is oxidized to Fe?O?. The copper matte contains less than 1.5% sulfur. The flue gas with SO? content of 10%–14% is used for sulfuric acid production. Hot pressing of matte involves adding a small amount of flux to the copper matte, mixing it, and hot-pressing it into a lump (see charge lumping). Reduction smelting in a low-shaft blast furnace involves adding a mixture of coke and lump anthracite as fuel to the low-shaft blast furnace along with the lump, with a coke ratio of 14% for smelting. Due to the short height, the residence time of the charge in the furnace is short, and during the reduction smelting process, the copper oxide is reduced to metal, forming black copper with a copper content greater than 94%; while Fe?O? is only reduced to FeO, which then reacts with silica and other fluxes to form slag. The slag contains 2.0%–2.5% copper, and the direct recovery rate of copper is 96%. The blast furnace air contains 23%–24% oxygen, and the use of oxygen-rich blast furnace air aims to minimize the sulfur remaining in the matte entering the flue gas. If the slag is (see copper smelting slag), black copper with a copper content of 75%–80% and an iron content of 10%–15% can be obtained. The discarded slag contains 0.4%–0.5% copper, and the recovery rate of copper in the electric furnace is 75%. The total recovery rate of copper from blast furnace smelting and electric furnace exceeds 98%. The recovery rate of copper using the grinding and flotation method (see high nickel grinding and flotation separation method) can also reach 98%. In 1975, R.O. William of Amax Company in the United States proposed the reduction smelting of copper in a low-shaft blast furnace and conducted small-scale, intermediate, and production-scale tests. This method eliminates intermediate processes such as sintering and blowing, which are prone to pollution, compared to traditional copper smelting methods, offering advantages such as smaller flue gas pollution, lower sulfuric acid production costs, and reduced investment in plant construction. However, due to the poor quality of the black copper and the difficulty in economically and effectively recovering the low-concentration sulfur dioxide flue gas from the blast furnace, it had not yet achieved industrial application by the late 1980s. (Wang Dequan)
ISa Smelting Process of Lead (ISa Smelting Process of Lead) is a lead smelting method that produces crude lead by melting sulfide lead concentrate through injecting air and coal powder into the molten charge using nozzles inserted into the top of two vertical furnaces. It is also known as the SIRO process. This method is a direct lead smelting technology developed jointly by Mount Isa Mines Limited of Australia and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). A demonstration facility built by Mount Isa Mines Limited, with a daily processing capacity of 5 tons of sulfide lead concentrate, operated from 1983 to 1986 and demonstrated good smelting performance. The company built an ISa Smelting Process of Lead plant with an annual output of 600,000 tons of lead in 1990.