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The disposal of red mud, which is a solid waste that is generated during the extraction of alumina from bauxite, is one of major problems faced by the aluminum industry. Alkali in red mud seeping under the soil may pollute land and water. The Northeastern University, China, has proposed a calcification–carbonation method to deal with low-grade bauxite or red mud. Its main purpose is to change the equilibrium phase of red mud to 2CaO·SiO2 and CaCO3 hydrometallurgically, so that recomposed alkali-free red mud can be widely used. We conducted calcification transformation experiments using diasporic bauxite sampled from Wenshan, and investigated the effects of parameters such as diasporic bauxite grain size, temperature and treatment time on the calcification transformation digestion rate, which is also termed the calcification transformation rate (CTR). The main phase in the calcification transformation slag (CTS) is hydrogarnet with different grain sizes. The CTR increases with decrease in diasporic bauxite grain size, or increase in temperature or reaction time. The CTR reaches a maximum of 87% after 120 min reaction at 240°C. The Na2O/Al2O3 ratio decreases with increase in temperature and reaches 1.5. The sodium content in the CTS decreases with increasing reaction time and is lower than that in the red mud treated using the Bayer process (4–12%).

Titanium has a great effect on the digestion of bauxite in the Bayer process because it reacts readily at high temperatures in alkaline sodium aluminate solution. Under this consideration, the hydrothermal conversion of Ti-containing minerals in the system of Na2O–Al2O3–SiO2–CaO–TiO2–H2O with increased temperatures was studied based on the thermodynamic analysis and systematic experiments. The results show that anatase converts to Al4Ti2SiO12 at low temperatures (60–120 °C), which is similar to anatase in crystal structure. As the temperature continues to rise, Al4Ti2SiO12 decomposes gradually and converts to Ca3TiSi2(Al2Si0.5Ti0.5)O14 at 200 °C. When the temperature reaches 260 °C, CaTiO3 forms as the most stable titanate species for its hexagonal closest packing with O2− and Ca2+. The findings enhance the understanding of titanate scaling in the Bayer process and clarify the mechanism of how additive lime improves the digestion of diaspore.

Processes of chemical alumina preparation of high alumina content fly ash raw materials are put forward in order to solve the problems of bauxite resource shortage in China and high value application of fly ash. High white aluminum hydroxide and Pseudoboehmite can be obtained by sintering process with the precipitation and carbonate decomposition. 4A zeolite is prepared through the pre-roasting and synthesis process, and activated aluminium oxide is prepared through the acid leaching and pyrolysis method. Typical experiments for preparing different kind of chemical alumina products are presented as well. Whiteness, porosity, pore volume, crystalline and other key parameters of chemical alumina products determined by XRD and ASAP match the industry requirements well.

Molten MgCl2 generally sold as a kind of waste at low price after cooling, which caused the waste of resource and energy. In order to solve the problem, a new method named “situ pyrolysis of molten magnesium chloride” was proposed. The molten MgCl2 produced by vacuum distillation in magnesium thermal reduction process was treated by the direct oxidation thermal decomposition method to produce super fine MgO with high purity. The magnesium produced by thermal reduction of MgO could be returned to the boiling chlorination of high titanium slag. The new cycle of magnesium and chloride in titanium sponge production was achieved. Based on the thermodynamic analysis of the reaction between O2 and MgCl2, the single factor experiments had been done. The optimal reaction condition was determined and the impact of each factor in the pyrolysis process was studied.

A novel method was developed to prepare aluminium via fluidizing chlorination with untraditional aluminum resources as raw materials. The main steps in this method were: alumina transformed into aluminium chloride through fluidizing chlorination; aluminium chloride reacted with NaOH solution for aluminium hydroxide and NaCl; NaOH and Cl2 were recycled from NaCl solution by electrolytic process. The new process for preparing aluminium resources by fluidizing chlorination method was proposed to realize efficient separation of the valuable components in non-traditional aluminum resources such as fly ash or low grade bauxite, silicon in untraditional aluminum changed into SiCl4 in fluidizing chlorination which could be used as raw materials for high purity Si products. Furthermore, the tailings emission of this process was quite lower than that of Bayer process. This paper mainly introduce the principle of this new process, the thermodynamics of fluidizing chlorination is analysis as well.

The novel calcification-carbonation method was proposed to process the diasporic red mud discharged from Bayer process alumina plant. In this study, Batch experiments were performed to evaluate the potential effects of important parameters such as temperature, amount of CaO added, CO2 partial pressure and carbonation cycles on the recovery of alkali and alumina. The results showed that 78.74% alumina was recovered from the diasporic red mud with decreases in the mass ratios of Al2O3 to SiO2 (A/S) from 1.27 to 0.27. The Na2O content in the processed red mud was less than 0.3 wt%, and it can be used as a construction material.

In this paper, the thermodynamics and kinetics of nature rutile carbochlorination in a fluidized-bed were investigated. The thermodynamic calculations of TiO2–C–Cl2 system show that when C is excess in the solid phase, titanium tetrachloride and carbon monoxide can exist stably. At high temperature, the reaction with CO as the product is the dominant reaction. The appropriate reaction conditions are as follows: reaction temperature of 950 °C, reaction time of 40 min, carbon ratio of 30 wt% of rutile, natural rutile particle size of −96 μm, petroleum coke size of −150 μm, and chlorine flow of 0.036 m3·h−1. Under the above conditions, the reaction conversion rate of TiO2 can reach about 95 %. This paper proposed a reaction rate model, and got a rutile chlorination rate formula, which is generally consistent with the experimental data. For the TiO2–C–Cl2 system, the reaction rate is dependent on the initial radius of rutile particle, density, and the partial pressures of Cl2. From 900 to 1,000 °C, the apparent activation energy is 10.569 kJ·mol−1, and the mass diffusion is found to be the main reaction-controlling step. The expression for the chlorine reaction rate in the C–Cl2 system is obtained, and it depends on the degree of reaction, the partial pressure of Cl2, and the size of rutile particle.

The process of pressure leaching the converter vanadium slag with waste titanium dioxide without roasting was studied. Mineralogy analysis indicates that the converter vanadium slag contains mainly three mineral phases: magnetite, titanium magnetite, and silicate phase. Vanadium is in combination with iron, titanium, manganese, aluminum, and silicon. The impacts of leaching temperature, leaching time, stirring speed, liquid-to-solid ratio, and initial leaching agent concentration were investigated on the waste titanium dioxide leaching process. The results indicate that under the optimal conditions, the vanadium and the iron leaching rates are 96.85 % and 93.50 %, respectively, and the content of titanium is 12.6 % in the residue. The main mineral phases for the residues under the optimal operation conditions are quartz, ilmenite, anatase, and silicate phase, and the residues can be reused as the extraction of titanium raw materials for titanium dioxide production technology by the sulfate method.

Aluminum industry is one of the most important industries in China’s nonferrous metal metallurgy industry. With the development of output in alumina and the improvement of its production technology, China’s high quality bauxite resources are difficult to meet. Under this condition, “Calcification-Carbonation Method” was put forward to deal with middle-low grade bauxite and red mud by Northeastern University, the main purpose of this method is to change the balance phase of red mud into 2CaO•SiO2 and CaCO3 with hydrometallurgical process. Through treatment by “Calcification-Carbonation Method”, A/S of the new structure red mud lowed below to 0.5 and the Na content lowed below to 0.3%, the red mud could be used in cement industry directly. This paper mainly introduced the technological idea and principle of new method, process comparison and typical experiment results is given as well.

With the rapid development of China’s aluminum industry, deficiency of high-quality bauxite reserves has become a bottleneck restricting for the healthy development of China’s aluminum industry. According to these issues, “Calcification-Carbonization Method” was purposed by Northeastern University for alumina production by using low grade bauxite. This paper researched on the transformation and separation performance in the new method. The experiment results indicated that: Al, Fe, Si transformed into hydrated garnet at 180°C and 245 °C through calcification treatment, and silicon phase changed into 2CaO • SiO2 through carbonization treatment. The settling performance of calcification slurry by using gibbsite is near to that of bayer process, when the settling performance by using diaspore get worse because of the solid content is higher than that of bayer process. Under the pressure of 0.18MPa, the filter constant of calcinated slurry are 4.18 × 10-5m2/s and 1.15 × 10-4m2/s for diaspore and gibbsite.

With the rapid development of China alumina production, efficient utilization of plentiful low grade high-iron bauxite has received widespread attention in the aluminum industry. Based on this, “calcification-carbonization-direct reduction” method is proposed for extracting effectively valuable metals Al and Fe from high-iron bauxite. The research results indicate that: after the calcification-carbonization process for high-iron bauxite, leaching rate of Al2O3 can reach 83.67%, higher than extraction rate of Al2O3 through Bayer method. Then, direct reduction of calcification-carbonization residue is investigated. Metallization ratio of Fe is 80.5% when reduction temperature and time is 1050°C and 2h respectively. Moreover, metallization ratio of Fe can reach 93.6% with the addition of additive A. After the “calcification-carbonization-direct reduction” process, valuable metals Al and Fe can be extracted effectively from high-iron bauxite. The main component of final residue is CaCO3 and CaSiO3, which can be directly applicable to the cement industry.

With the rapid development of the electric power industry in China, the amount of fly ash discharged is growing day by day, which brings great harm to the production industry and people’s living conditions. In this article, hydro-thermal method and alkali fusion -hydro-thermal method have been used to prepare 4A zeolite from coal fly ash. The results indicate that the optimum conditions (calcination temperature 850°C, ratio of silicon to aluminum in raw material 0.8, alkalinity of NaOH 2.5mol/L, the aging time 6h, crystal temperature 90°C and crystal time 24h), the specific surface area of the prepared zeolite is 605.6m2/g. The synthesized 4A zeolite has a uniform particle size with a narrow distribution. Its shape is cube and in rules, and all its properties are close to 4A zeolite purchased in the market.

Fly ash is a very important unconventional aluminum resource in which the alumina content comes up to 40 ~ 60% in part of China. It has great economic and environmental value to exploit the recycling method of fly ash and produce high value-added multi-alumina products. In this paper, preparation of pseudo-boehmite by using Inner Mongolia Datang fly ash sintering clinker has been investigated. After a series of processing under optimized conditions (dissolution at 80°C, 60min, liquid solid ratio 4:1, first stage desilication 120min, 170°C, sodium silicon slag 100 g/l, sec-stage desilication 120 min, 90°C, CaO content 15 g/l), the silica ratio of the solution reaches up to 838, which conforms to the requirement of the industry. The pore volume of the seed precipitation product reaches 0.8291cm3/g, which is almost the same with standard sample. The Na2O content of pseudo-boehmite prepared is below 0.3%, which can meet the sodium content requirements of general catalyst.

Calcification-carbonization is a new method of producing alumina with low-grade bauxite (red mud). Low-grade bauxite (red mud) are all converted into garnet hydration during calcification process, then garnet hydration are treated with CO2 and the new structure red mud are gained by digestion. Main components of the new sturcture red mud are CaSiO3 and CaCO3, it can be used directly for cement industry and Bauxite resource recycling is carried out. A series of experiments were done by our team and confirmed that the new method was feasible, A/S of new structure red mud dropped to 0.21 and the content of sodium is under 0.2%. Process calculation software METSIM was used to design and simulate the new process of producing alumina with low-grade bauxite (red mud) by calcification-carbonization method, and its economic with series process and bayer process was analyzed.

Now the using of process simulation software is more and more widely in many fields especially in chemistry and metallurgy plant designing. The process simulation software provides great convenience for experts and engineers, they can analysis the new process and calculate the heating/material balance by process simulation software, and calculate complex process that the traditional tool EXCEL can not do. The paper introduced the current major process simulation software, includes mainly introducing the application of METSIM and SYSCAD software in metallurgical process, and summary the computational process of them by a few examples, at the same time the application status of the process simulation software was pointed out.

Research on the leaching performance of fly ash of Shanxi, Chongqing and Western Inner Mongolia. Analyze the existing forms, crystallinity and package situation of Al-Si phase in fly ash from different areas by using SEM and XRD. Effect of fractionation of Al-Si phase in fly ash on the leaching performance from the view of mechanism was investigated as well. Leaching experiments and analysis indicate that: the leaching rates of Al203 in fly ash from the there different areas are 97.41%, 68.94% and 23.61% respectively, under the conditions of solid-liquid ratio 1:20, rotary speed 500rpm, leaching time 120min, sulfate concentration 20%, particle sizes −74µm. Leaching performance of fly ash in Western Inner Mongolia is better than that in other two areas. The main reason for different leaching performance of fly ash from different areas is the difference in crystallinity, encapsulated glass phase of Al-Si phase in fly ash. The crystallinity for Western Inner Mongolia is 75.98%, while there is no non-crystalline phase in fly ash from other tow areas, The average FWHM of XRD diffraction peak of Al-Si phase are 0.641, 0.3324 and 0.1107, respectively. The crystallinity of fly ash in Western Inner Mongolia is worst among the there areas, and its content of glass phase is also lowest among them, so its activity is obviously higher than that of other two areas.

This paper investigates the changes of phase and apparent morphology under the combined effects of an intense magnetic field and temperature field and the effect law of different roasting conditions on the digestion performance of roasted diaspore. The results indicated that roasting pretreatment under high magnetic fields can change the microstructure and improve the digestion properties of bauxite. The reasonable roasting conditions with intense magnetic field are as follows; the roasting temperature is 550°C, roasting time is 60min and the magnetic field intensity is 6T. The digestion rate of alumina of the roasted ore is 84.17% and the digesting liquid ratio is 1.39 while the digesting temperature is 190°C with the digestion time of 60mins. The digestion rate of alumina of the roasted ore increases to higher 52.85% than that of the raw ore, but the digesting liquid ratio is decreased to lower than 0.99 of the raw ore under the above roasting conditions. The digestion temperature of roasted ore decreases by 30°C compared to the raw ore.