Effect of mineral matter

Activated carbon obtained from coal and its ash-content-reduced derivatives (obtained by a combined treatment with acidic solutions) were used to investigate SO2 adsorption capacities [348]. The activated carbons with reduced ash content showed better SO2 uptake than the initial carbon, even at lower burn-off values. This particular behavior of low ash activated carbons was linked to the alteration in pore size distribution, and to the redistribution of part of the mineral matter in the carbonaceous matrix, which occurs during the initial acidic treatment of the raw coal [348]. 

The presence of ash can also influence the adsorption mechanism either via ion exchange or due to the catalytic effect of an inorganic matter. The adsorption feature of activated carbon combined with iron oxides in composites have been reported for a wide range of contaminants in water. The cmnposites materials show high adsorption capacities fiir phenol, chloroform, chlorobenzene and organic %es in aqueous solution [353]. 

In the case of metal removal, Lorenzen and co-workers found that As(V) is more effectively removed from solution ly using activated carbon with a high ash content Particularly, the presence of Cu(ll) on the carbon improved the arsenic removal capacity [337]. 

The effect of the residual inorganic material of commercial carbons on their polarity and on the adsorption of certain contaminant in drinking water has been investigated ly Baker and co-woikers [354]. They used wood-based, phosphoric activated carbons with various contents of residual phosphates to study the effect on tte adsorption performance of both metallic species and organic compounds. The authors interestingly reported a direct relationship between the phosphate level on the carbon and the decrease in their adsorption capacities [354]. 

---

The Effect of Mineral Matters on the Decomposition Ethers. Recently, the effect of mineral matters of coal on the coal liquefaction has received much attention. It was shown that small amounts of FeS or pyrite are responsible for the hydro-genative liquefaction of coal. Therefore, it is interesting to elucidate the effect of mineral matters of coal on the decomposition rate and products of aromatic ethers, and so three diaryl ethers were thermally treated in the presence of coal ash obtained by low temperature combustion of Illinois No.6 coal at about 200°C with ozone containing oxygen. 

The effect of mineral matter is so small that it is completely negligible compared to the combined specific surface of the macropores and transition pores in coals with scattering curves which have a shoulder. 

The practical motivation for understanding the microscopic details of char reaction stem from questions such as How does the variability in reactivity from particle to particle and with extent of reaction affect overall carbon conversion What is the interdependence of mineral matter evolution and char reactivity, which arises from the catalytic effect of mineral matter on carbon gasification and the effects of carbon surface recession, pitting, and fragmentation on ash distribution How are sulfur capture by alkaline earth additives, nitric oxide formation from organically bound nitrogen, vaporization of mineral constituents, and carbon monoxide oxidation influenced by the localized surface and gas chemistry within pores ... 

The effect of mineral matter present In subbituminous coals was Investigated by carrying out non-catalytlc liquefaction with hydrogen and synthesis gas. Most of the twelve coals studied could be readily liquefied to a low viscosity and low sulfur oil In the absence of added catalysts with synthesis gas at temperatures of 400-450°C and operating pressures of 3800-4400 psl. Comparison with coal liquefaction using pure hydrogen at optimum liquefaction temperature of 425°C and pressure of 3800-4000 psl resulted In lower conversions, lower selectivity to oil and a product with higher viscosity. 

Reid, W.T., "The Effect of Mineral Matter in Coal on Ash Behavior in Large Boiler Furnaces", Presentation to the ASME Committee on Corrosion and Deposits from Combustion Gases, September 29, 1971. 

Jackson, P., "From Mineral Matter to Deposits in PF-Fired Boilers, Part 1 The Behavior of Mineral Matter in the Flame", Pulverized Coal Firing - The Effect of Mineral Matter, T. 

Large uncertainties exist in the apparent and intrinsic rate of char combustion. Estimates of the rate of char combustion within the range of uncertainties can result in over designed or under designed boilers. A review (2) has shown that one of the major uncertainties in the rate of char combustion is the catalytic influence of mineral matter. This paper reviews the available information on the catalytic effects of mineral matter and concludes that many coals contain sufficient sodium and calcium to increase the rate of char combustion by a factor of 100 at low temperatures. However, insufficient information is available to assess the influences of catalysis by mineral matter at combustion temperatures. 

The study regarding catalysis in coal liquefaction can be broadly divided into two groups (1) effects of mineral matter present in the coal slurry itself and (2) effects of externally added catalysts. 

Mukherjee, D.K. and P.B. Chowdhury. Catalytic Effect of Mineral Matter Constituents In a North Assam Coal on Hydrogena-tlon. Fuel 55 (1976) 4. 

The raw lignite was demineralized in order to study the effect of mineral matter on the properties of the final product. Removal of the inorganic constituents of the raw coal was accomplished by acid washing of the initial material with HCl and HF acid solutions [45]. About 120 ml of 5N HCl were added to 18 g of coal in a glass beaker. The mixture was stirred for one hour at room temperature. The treated coal was then filtered and washed with distilled water. Subsequently, the coal was mixed with 120 ml of full strength (22N) HF in a plastic beaker. This mixture was also stirred for one hour at 25 2°C, then filtered off and washed. The coal residue was then mixed with 120 ml of full strength (12N) HCl for a third treatment, for one hour at the same temperature. Finally, the coal was filtered, washed, and dried at 373K in an inert atmosphere. 

Garcia-Garcia, A., et al., NO reduction by potassium-containing coal briquettes Effect of mineral matter content and coal rank. Energy Fuels, 11(2), 292-298 (1997). 

---