Qiang Zhong

Investigation of Coal Tar Pitch Binder for the Production of Formed Coal Briquettes for COREX from High Volatile Coal Powder

Lump coal with high volatility is used for providing heat and reductive gas, and ensuring permeability in COREX. However, it is apt to be pulverized in transport and storage process. Therefore, comprehensive utilization of the pulverized coal to produce coal briquettes with appropriate binders is significant, among which the molasses binder cannot meet the technological requirements. In this paper, coal tar pitch binder and BJ additive were used in briquetting and carbonizing process of coal powder. The results showed that BJ effectively activated cold state cohesiveness of the pitch and make it bond the coke particles to a firm briquette at room temperature .Carbonizations of coal and coal tar pitch achieved obvious constriction and formed a carbonized skeleton. The drop resistance of wet briquettes reached over 50 times/1meter. When cured at 1000°C for 1h under nitrogen atmosphere, the compressive strength of carbonized briquettes came to 6.43 Mpa.

Cohering Behavior of Coal Ash with Pellet Scrap Powder and Relationship Between Coal Ash and Kiln Ringing

The occurrence of different ringing behaviors in oxidized pellet kiln for two kinds of coal (A and B) with similar properties, is difficult to explain based on the relationship between kiln ringing and coal properties. In this paper, the interaction of coal ash with pellet scrap powder was considered by studying the cohering behavior of powders consisting of them. The results showed that the cohering briquette strength of pellet scrap powder increased considerably when mixed with a small amount of coal ash; a maximum could be reached when the mass percent ratio of coal ash was 1.5%; the strength of powder mixed with coal B ash was always higher in same firing system. This obviously illustrated that coal B caused a more serious ringing problem. The relevant mechanism was that the stronger reactivity of coal B ash made cohering briquette have a more perfect crystallization and a more compact structure.

Thermogravimetric Analysis of Coal Used in Rotary Kiln of Iron Ore Oxide Pellet

Thermogravimetric analysis (TGA) has been used to research the pyrolysis and combustion processes of coal used in rotary kiln of iron ore oxide pellet. Furthermore, the effects of air flow and oxygen concentration on the combustion behavior of coal were examined with TGA. The results showed that two individual stages can be distinguished for the pyrolysis of coal, the water evaporation stage and the de-volatilization stage. And the information on ignition and burnout characteristics can be obtained from the combustion process analyzed by TGA. Large air flow almost has no effect to the combustion process except that it enhances combustion intensity. However, the combustion process is further accelerated under oxygen-enriched conditions. With all experimental results, it could provide an attractive approach of analyzing coal for the rotary kiln process.

Viscosity Property of Gold-Antimony Smelting Slags by Blast Furnace

Viscosity of slag determines the production efficiency, energy consumption and distribution of elements between metal and slag, which is very important for pyrometallurgy. Slag of gold-antimony ore blast furnace smelting has seldom been studied. In this paper, the viscosities of gold-antimony ore smelting slags of different composition have been studied by the rotating cylinder method. The results showed that, for a slag of 38.95% SiO2, 16.17% CaO, 25.97% FeO, 10.25% Al2O3, 5.17% MgO, the viscosity can be decreased by reducing 3.24%–8.5% SiO2 or increasing 3.31%–9.56% CaO content. Complex SixOyz- from SiO2 acts as the main cause for the high viscosity in a slag of high SiO2. The increasing of CaO causes the decreasing of the amount of SixOyz- and the O2- dissociated from CaO breaks the complex SixOyz-, which can decrease the viscosity. Viscosity of different composition slag in the appropriate range temperature can be calculated from the Arrhenius equation.