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In this paper, the problems of co-production process of cement and sulfuric acid from phosphogypsum in industrial production are briefly described. The gypsum decomposition mechanism is introduced. The results indicated that the decomposition temperature of gypsum can be reduced using coal as reducing agent, which is beneficial to reduce energy consumption and production cost. The research status of sulfur-containing low calcium cement from gypsum and high-strength low calcium Portland cement are also introduced. It will be the development trend to produce high-strength and low-calcium Portland cement with phosphogypsum. The early strength of high-strength and low-calcium Portland cement can be improved by stabilizing the high temperature structure of dicalcium silicate, changing the hydration environment and carbonation curing. Sulphuric acid co-production cement from phosphogypsum can be manufactured by equipment improvement from Portland cement industry, which the distribution of phosphogypsum is concentrated and Portland cement industry has excess production capacity in China. The idea will save investment and be beneficial to the resource utilization of phosphogypsum. [ABSTRACT FROM AUTHOR]

Sediment is one of the major sources of internal pollution in lakes. Pollution control of contaminated sediment has become a hot topic in the world. In this paper, used brick powder was chosen as a passivator for remediating nutrient-laden sediment, and the relationships between brick powder dosages and pollutant indexes in the overlying water and sediments were determined. The results showed that in the overlying water, brick powder could be used to reduce total phosphorus (TP) concentrations; however, it had no effects on total nitrogen (TN), chemical oxygen demands, pH, and oxygen. In the sediments, organic matter (OM), TN, TP, Fe–P, Al–P, and Ca–P concentrations were decreased, while organic phosphorus (Org-P) was increased. Using principal component analysis, it was found that brick dosage could significantly affect the sediment physicochemical properties. A positive correlation was established between brick dosage and Org-P, and a negative correlation with TP and organic matter. An optimal dosage of 20 g of brick powders was determined to be effective in the sediment remediation of this study. [ABSTRACT FROM PUBLISHER]

Abstract: Zinc-blende B x Ga1− x As alloys have been successfully grown on exactly oriented (001)GaAs substrates using triethylboron, trimethylgallium and arsine sources. The growth has been accomplished in a vertical low-pressure metalorganic chemical vapor deposition (LP-MOCVD) reactor. Boron incorporation behaviors have been extensively studied as a function of growth temperature and gas-phase boron mole fraction. The evolution of surface morphology was also observed. The maximum boron composition of 5.8% is obtained at the optimum growth temperature of 580°C. RMS roughness over the surface area of 1×1μm2 is only 0.17nm at such growth conditions. Based on the experimental results, it has been clearly shown that boron incorporation will decrease significantly at higher temperature (>610°C) or at much lower temperature (⩽550°C). [Copyright &y& Elsevier]