Advanced Materials Research Vols. 524-527

Abstract: Rare earth is one of the most important strategic resources related to the national security and development. Nowadays, all countries over the world have a fierce competition on the rare earth. Although China has rich rare earth resource, the advantage decreases gradually due to various factors such as the technology level, waste of resource and so on. It goes against China's long-term development strategy of mineral resource seriously. So it is urgent to carry out rare earth mineral lands reserve system. In such background, according to the existing research results at home and abroad, this paper mainly summarizes the current supply and demand situation of rare earth in China, the conception and characteristic of mineral reserve, factors that affect the rare earth reserve scale, and then establishes a basic calculating model of rare earth mineral lands reserve scale.

Abstract: Sialon-based eco-materials were synthesized by using the gold mineral tailings that containing abundant Si and Al elements as the major raw material with minor additives through the carbothermal reduction nitridation route. This study realized the conversion of eco-materials from solid waste, gold mineral tailings. The effects of sintering temperature, holding time and x value during carbothermal reduction nitridation process on the phase composition and microstructure of as-fabricated Sialon-based materials were explored. The XRD results indicated that when sintering temperature is 1550°C, holding time is 6h, and x value is 1.0, Ca-α-Sialon/SiC/Fe₃Si composites was successfully synthesized. The relative content _{Subscript text}of each phase in the products is I(α-Sialon): I(SiC): I(Fe₃Si)=82:10:8. The SEM images showed the densificated microstructure and uniform grains with the long column shape.

Abstract: It concerns about issues of dust pollution of three feeder which in the underground passage under the storage warehouse of Inner Mongolia Datang International Xilinhaotes Mining Company Limited.By inspections and investigations in the field,according to site-specific circumstances and local climatic conditions,we had implemented comprehensive renovation project of coal dust of feeder in underground passage,and achieved remarkable and effective governance results.

Abstract: skarn-type scheelite; mineral processing system; tailings; lead; arsenic; distribution regularity

Abstract: Coal gangue is one of the largest industrial solid wastes in China; the comprehensive utilization of coal gangue has important social, economic and environmental benefits. In this paper, the coal gangue and comprehensive utilization have been discussed in detail. Through the survey results, expounds the development of the use of coal gangue and improve work with practical significance.

Abstract: In order to investigate the different forms of sulfur in the cement, certain amount gypsum were blended into cement raw meal, which was pre-prepared by the cement plant. The above blends were firstly calcined to form cement clinker in a furnace at ~1450oC. Serious chemical solutions, such as, salicylic acid - methanol (SAM), potassium hydroxide - sucrose (KOSH) and acetic acid, were used to select the extractors from laboratory clinker. After the separation of silicate phase, iron aluminate phase, and intermediate phase of minerals, the trace amount minerals phase were enriched. Corresponding analytical methods, such as, XRD, XRF, SEM-EDS, were used to analyze the different sulfur type during the three-step extraction process. As a result, the trace sulfur minerals of cement was identified as three major forms of（KAl(SO4)2）,C4A3S, and（CaSO4）

Abstract: Abundant of bauxite in China couldn’t be used to process alumina with Bayer process due to it is contain the high silicon. Many of low-grade bauxite have not been fully utilized, and caused many waste of resources. So the bauxite flotation to desilicication of low-grade bauxite will have a very important significance for China's aluminum industry. This paper reports an innovative development: the separation of silicon from bauxite with two stages by the stage grinding and stage flotation via the direct flotation, and obtained the high quality bauxite concentrate, the flotation index is favorable. The raw ore contains Al₂O₃ 60.78%, SiO₂ 20.84%, the A_l2O₃ to SiO₂ mass ratio (A/S) is 2.92, the main gangue minerals are kaolinite, quartz, pyrophyllites etc. Through the first flotation by the coarse grinding and separation a part of the silicon, then the rough concentrate for the secondary flotation after the regrinding and separation other part of the silicon, obtained the qualified concentrate. The rough concentrate via the five times clean flotation after regrinding. The closed-circuit test obtained the indexes with the concentrate contains Al₂O₃ 70.23%, SiO₂ 8.65%, the A/S is 8.12, the recovery of Al₂O₃ is 72.49%. This process can reduce the pollution of gangue minerals to bauxite at the condition of fine grinding, prevent over crush of bauxite, and reduce the impact of experiment of flotation by slime.

Abstract: Through adding keratin additives to coal washing water with SS removal rate as an index, this paper draws a conclusion that the best operation conditions of treatment are: adding feather keratin flocculation additives by 2 g / L to the wastewater of pH value 5～7, treating it at 20～30°C for 30 minutes. The SS removal rate is over 98%，meanwhile COD removal rate can reach 34% under the conditions.

Abstract: SYB2# (a category of hydroxamic acid) was employed as the collector of ilmenite flotation. Sodium carboxymethyl cellulose was employed as the depressor of gangue, and sulphuric acid as the pH adjustor of flotation. The effect of pH values on the recovery of ilmenite and gangue was investigated on the condition with (or without) depression respectively. The results demonstrate that pH value does not have any obvious effect on the recovery of ilmenite or gangue when no depressor is added. On the contrary, the pH value plays an important role in ilmenite flotation when depressor is added. To be specific, the recovery of ilmenite increases obviously with pH value decreasing. Having a comparison among the recoveries of ilmenite with different pH values adjusted by sulphuric acid, hydrochloric acid and nitrating acid, it is concluded that sulphuric acid produces anti-depression effect on ilmenite depressed by sodium carboxymethyl cellulose.

Abstract: White mud is generally known as the residue of soda ash production by ammonia-soda process. The treatment of it has been one problem in soda ash industry due to the large amount of production, strong alkalinity and corrosiveness. In China, the treatment of white mud is stacking currently, which not only occupying land but also causing environment pollution. The main composition of it is the calcium carbonate. If white mud replaces the limestone as the desulfurization agent in wet Flue Gas Desulfurization (W-FGD) system, it can attain the goal of treating the waste with another, achieve the circular economy between enterprises, and reduce the desulfurization cost significantly. In this paper, the research of white mud in 660 MW Unit W-FGD systems was investigated. Study shows that the properties of white mud and limestone are significantly different. Because of smaller particle size and active MgO, the alkaline and reaction activity of white mud are better than that of limestone, results to higher desulfurization rate and lower running cost. However, the purity of white mud is lower because of CaSO4, Cl-, and other impurities, so the dewatering system of gypsum needs to increase output by about 17%; the output of the slurry feed system needs to be increased by about 30%; the discharge capacity of wastewater needs to be increased by about 23 t/h.