Evaluation of Grindability Behaviors of Four Different Solid Fuels Blending by Using the Hardgrove Mill

Grindability measurements are widely used in mineral and coal processing industry to determine resistance of materials to comminution.Grindability measurement as testing methods can be divided into two general categories; the Bond and the Hardgrovegrindabilities. Grinding characteristics of the mineral or coal blending have been studied by several researchers over many yearsand a wide range grinding variables has been investigated. In this study, because of the simplicity and the potential usage of themethod for the determination of the grindability of coals and their blending in a comparative scale, a Hardgrove mill were used toinvestigated the grinding behavior of four different solid fuels and their blending. Grindability of four different solid fuels such as;petroleum coke, coke coal, lignite and bituminous coal and their binary, ternary and quaternary blending were investigated by theHardgrove grindability test. The test results indicated that determine the existence of a very good relation between the Bond andthe Hardgrove grindability of the fuels, and relationship between experimental and calculated HGI values of the fuels blendingwere also shown as a very good. However, there is not obtain a good relation between proximate analysis results of the solid fuelsand HGI values of fuels blending.

Densification of Biocarbon and Its Effect on CO2 Reactivity

Charcoal is an interesting reducing agent because it is produced from biomass which is renewable and does not contribute to global warming, provided that there is a balance between the felling of timber and growth of trees. Biocarbon is a promising alternative to fossil reductants for reducing greenhouse gas emissions and increasing sustainability of the metallurgical industry. In comparison to conventional reductants (i.e., petroleum coke, coal and metallurgical coke), charcoal has a low density, low mechanical properties and high CO2 reactivity, which are undesirable in ferroalloy production. Densification is an efficient way to upgrade biocarbon and improve its undesirable properties. In this study, the deposition of carbon from methane on three types of charcoal has been investigated at 1100 °C. CO2 reactivity, porosity and density of untreated and densified charcoal were measured, and results were compared to metallurgical coke. Surface morphology of the charcoal samples was investigated by using scanning electron microscopy (SEM). SEM confirmed the presence of a deposited carbon layer on the charcoal. It was found that the CO2 reactivity and porosity of charcoals decreased during the densification process, approaching that of fossil fuel reductants. However, the CO2 reactivity kept higher than that of metallurgical coke.

Contents of Ecotoxic Elements in Polish Coking Bituminous Coals and in Products of Coking

Ecotoxic elements include the ones which have a negative impact on human health and the environment, among others, mercury, arsenic and lead. Hard coal is a fuel which contains significant amounts of ecotoxic elements and the processes of coal combustion, coking and gasification are one of the main sources of their anthropogenic emission. In the coking process, individual ecotoxic elements in various proportions remain in coke and are released to the raw coke oven gas. During the cleaning and cooling of coke gas, ecotoxic elements are distributed between purified coke gas and other coking byproducts. In the paper, the measurement results of the contents of selected ecotoxic elements in the Polish coking bituminous coals are presented, i.e. mercury, arsenic and lead. The examination results of their content in the products of the coking process i.e. coke, coal tar, BTX, sulfur, and purified coke oven gas are also shown. Coke is characterized by a much lower content of mercury and lead than coal, and by a similar content of arsenic. Among the coking products, sulfur and tar are characterized by the highest content of mercury. Coal tar also contains a high amount of lead.

Preparation and Characterization of AA6061 Aluminum Alloy Composite Reinforced With Different Contents of Blast-Furnace Slag by Powder Metalurgy

ABSTRACTThe constant search for the improvement of the performance of materials of industrial application, evaluated under aspects of weight reduction, greater resistance, greater resistance to wear and better thermal stability, among others, associated with the search for the development of ecologically viable products, that convert the context of environmental degradation in preservation and sustainability, reflects the need to conduct research that results in new materials. The objective of this work is to obtain composites of the AA6061 aluminum alloy reinforced with different contents of coke coal blast-furnace slag by powder metallurgy. The processing of these materials was done by sieving, mixing and compacting powders of reinforced aluminum alloy with 5, 10 and 15% of blast-furnace slag. The cold uniaxial compaction was realized at a pressure of 500MPa. The obtained materials were sintered at 580°C for 3h under inert atmosphere. Unreinforced aluminum alloy samples were also produced. The characterization of the materials was realized by density and hardness measurements and three-point bending tests. The analysis of its microstructure was realized by scanning electron microscopy. As results, the composites presented a homogeneous distribution of the reinforcing particles and also a progressive improvement of the hardness and the bending strength with the increase of the slag content, producing an increase of 79% in hardness and 128% in flexural strength, when compared to the material without reinforcement obtained by the same process. Such results give the coke coal blast-furnace slag a new possibility of exploitation in the metal-mechanical sector, besides contributing with the environmental issue.

Co-Combustion Characteristics of Semi-Coke and Coal Under Air Condition

In this work, the combustion characteristics of semi-coke, coal, and their blends under air conditions were studied. The influence of blending ratio on the combustion characteristics of blended fuels were investigated by thermogravimetric analysis. It was found that the co-combustion of semi-coke and bituminous coal was a complicated process rather than a simple linear superposition, with interaction effect occurring in the co-combustion process. The synergy occurred in the whole combustion process and it was analyzed quantitatively by comparing the interaction coefficient f and the relative root mean square error RMS. The combustion of semi-coke and the blends can be divided to three stages, as well as two stages of coal. In addition, the blends show better combustion behavior with enhancing bituminous coal proportion, and bituminous coal can improve the combustion behavior of semi-coke.