The article presents the results of studying the synthesis kinetics of hydrated magnesium carboaluminates and determines the key role of preceding thermal activation of a raw magnesium component and temperature in the process rate. The study covers the mechanism and conditions of co-crystallization of hydrated calcium and magnesium carboaluminates from the pre-activated natural Mg-containing raw material. It is found that the hexagonal structures of synthesized substances exhibit high regenerative ability. The paper offers a process and instrumentation diagram for synthesizing hydrated carboaluminates of alkali-earth metals in alumina production.
Complex mineral raw material, as alkali aluminum silicates, is an interest for aluminum industry, chemical industry and for the production of constructional materials. They are well represented in the earth's crust, characterized by the complexity of material composition and variable content of the main components such as alumina, silica and alkalies. They often occur where due to the geological conditions there is no bauxite, for instance, in the United States, Canada, Venezuela, Mexico, Iran, Egypt, Portugal, Spain, Bulgaria and other countries. At the present time for the Russian economy the nephelines from this list are the most valuable and have the great concern for the raw materials balance of the national aluminum industry. Because of limited reserves the bauxites proportion of alumina produced from nephelines by sintering is 40 % and in time this proportion will increase due to the involvement in the production of new deposits of alkali aluminum silicates. Many of foreign companies have also shown interest to the complex processing of ores. The investigation of technology is based on the method of sintering ore with limestone. As a result, the after-sintering mixture consists of alkali metal aluminates and dicalcium silicate; after-sintering mixture is leached by circulating alkaline aluminate solution, alumina, soda and potash are thrown out from the solution. Dicalcium silicate (nepheline sludge) is processed to Portland. For the investigated after-sintering mixture the tendency shows the increasing of optimum sintering temperature with the lowering Al 2 O 3 content. With the increasing of silicate module (SiO 2 / Al 3 O 3 ) of the initial alkali aluminum silicates charges the temperature of after-sintering mixture formation increases. After-sintering mixtures that are on base of alkali aluminum silicates have different microstructure and the degree of crystallization in which b-С 2 S and sodium aluminate is improved with a decrease of the aluminate phase amount. Results of investigations show a very limited solubility of aluminate phase in dicalcium silicate, which theoretically justifies a sufficiently high level of useful components chemical extraction in the processing of different types of alkali aluminum silicates by sintering.
The problem of auto-feeding of aluminum fluoride with high bulk density is discussed. The possibility of reducing the specific consumption of aluminum fluoride in relation to the rational choice of physical and chemical characteristics is studied.
The question of magnesium oxide application for purification of aluminate liquors of aluminous production is in a complex considered. The two-phasic process is offered for providing of magnesium hydrocarbo- and sulfuraluminates formation by interaction of magnesium oxide with aluminate liquors under conditions, corresponding to parameters of aluminous production. High sorption activity of received compounds is defined with reference to organic substances of aluminate liquors.
The thermodynamic analysis of aluminium hydroxide dehydration during calcination process at alumina production is carried out. The calcination of aluminium hydroxide is possible at ordinary pressure and temperature value more than 600 K. Diaspor dehydration process is possible by way of freezeout of water as an ice, water rendering or heating till decomposition temperature.
It is well known that lime is an effective additive which allows to increase the depth and speed of the extraction of alumina from bauxite by the Bayer process. The firing is one of the operations in thermochemical conditioning of bauxite, it is rational to enter directly on the lime-stone at firing of bauxite, eliminating the special operation of firing limestone and calcined material damping. In order to test this were carried out research on the firing of bauxite in the presence of calcium oxide, subsequent desiliconization of calcined bauxite and autoclave leaching bauxite concentrate.
The statistical analysis has allowed to reveal the additives essentially influencing process of formation of corundum. So, fluoric connections of sodium, calcium, aluminum, oxide of iron and chrome promote formation. Opposite influence is rendered oxide of sodium, by connections of lithium and a dioxide of the titan. Besides, influence of a dioxide of the titan and oxide of chrome is estimated.
Modern metallurgy pays more attention to chemical processes safety of staff and nature environment. One of the most hazardous branches in metallurgy is gold ores cyanidation. Researches on possibility to avoid cyanide leaching are carrying out during last thirty years. Cyanide competitors are thiosulphate and thiourea solvers. Within international cooperation between National Mineral Resources University and Lappeenranta University of Technology researches are devoted to tiosulphate leaching improvement. Main efforts are forwarded on process chemistry, however mass transfer processes of heterogenic systems are important as well. Therefore their optimization is planned to achieve by means of computer modeling based on particle image velocimetry.
Are considered the advantages and disadvantages of complex processing red mud to produce alumina, iron (cast iron) and cement on the area of alumina refineries and way of getting on them only transportable red mud – for shipping and recycling of new marketable products at operating enterprises.
The possibility of thickening and filtration for separation of heterogeneous disperse systems formed during the chemical conditioning of bauxite was investigated. It is shown that with increasing the ratio between liquid and solid phases of bauxite pulp thickening process indicators are improving. A similar influence provides of temperature increase of the process and the use of flocculants. The obtained results are compared with the indicators of condensation of red mud. The filter cloth was chosen for slurry concentrate bauxite, which provides the most rational regime filtration with the accumulation of sediment.
More and more attention is paying to research of feasible cyanide alternative leaching techniques due to increasingly growing concern to Mother Nature. After some serious cyanide accidents some countries have campaigned to ban cyanide in gold mining industry. Political alignments and concern about environmental have been reasons to find good and less-toxic alternatives to cyanide.One of the most promising leach reagents is stated to be thiosulphate because of its benign properties. Moreover it is suitable for sulphide and carbonaceous ores which present a problem for cyanidation.In the present paper number of experiments on research of thiosulphate leaching kinetic study as well as pretreatment of gold concentrate by wet oxidation with following leaching tests is presented.
The results of synthesis hydrocarboalyuminates of calcium (GKAK) using carbonate reagents of different nature and size distribution. A high activity of the lime sludge from causticising soda and food processing conversion of phosphogypsum, which allows us to recommend them for use in the process of obtaining GKAK. Installed limiting stage of interaction of internal diffusion of the reactants.
The results of laboratory studies on super deep desilication of alumina liquors based on hidrocarboalyuminat calcium supplements 4CaO×Al2O3×0,5CO2×11H2O in advance of entering into the process of working hydrogranat sludge. Obtained qualitatively new alumina liquors with a silicon module (weight ratio Al2O3/SiO2) of 50 000 units. Impact of type-ahead hydrogranat sludge to a desilication depth given from the viewpoint of heterogeneous catalysis.
Computer based modeling is increasingly strengthening its position in equipment designing, especially unique meeting particular needs of production line or certain plant of metallurgy. There are several reasons for that such as economic benefits, wide range of geometry available to be built and possibility of comprehensive study on materials reliability as well as virtual model testing in working regime.One of the most applied and therefore permanently developed program packages for fluid behavior modeling is Fluent product of ANSYS company. The package is being used for creation first physical and in future chemical model which will be capable to describe and predict process and reactions behavior of high quality taking place in gold leaching gas-liquid reactor with thiosulphate using.
The results of laboratory studies on super deep desilication of alumina liquors based on hidrocarboalyuminat calcium supplements 4CaO×Al2O3×0,5CO2×11H2O in advance of entering into the process of working hydrogranat sludge. Obtained qualitatively new alumina liquors with a silicon module (weight ratio Al2O3 / SiO2) of 50000 units. Impact of type-ahead hydrogranat sludge to a desilication depth given from the viewpoint of heterogeneous catalysis. The results obtained can be used to solve the problem of diversification of production in the complex processing of phosphogypsum in the synthesis calcium hydrocarboaluminates on the basis of fosfomel.
The theoretical basis of the synthesis of calcium hydrocarboaluminates 4CaO×Al2O3×mCO2×11H2O based on the CaCO3 in the aluminate-base system. We construct the isotherm of metastable equilibria in the system CaCO3 – 4CaO×Al2O3×mCO2×11H2O – 3CaO×Al2O3×6H2O – NaAl(OH)4 – NaOH – H2O at 50, 70 and 90°C.
Показано современное состояние алюминиевой промышленности России. Предложены пути развития сырьевой базы, создания комплексных безотходных технологий производства алюминия.
Рассмотрены варианты рациональной переработки промпродуктов титаномагниевого производства. Опробована технология получения металлического ванадия с использованием отработанного магниевого электролита и оксихлорида ванадия. При магние- и натриетермическом восстановлении хлоридов ванадия получен металл в форме порошка, кристаллов и губчатой массы.