GB759145A - Improvements in or relating to briquetting - Google Patents

Abstract

In a process for briquetting particulate moist or moistened material such as fuels, ores and fuel/ore mixtures the base material is mixed with a binding agent and the resulting mixture shaped, the binding agent being a hot tar pitch melt comprising (1) a coal tar pitch/"solubiized" coal mixture, or a coal tar pitch made by blowing with oxygen or an oxygen containing gas but in the absence of both steam and air together and (2) an aromatic compound constituted by two or three rings in an amount up to 40 per cent, by weight of the pitch tar melt. Suitable aromatic compounds are crude naphthalene, anthracene or phenanthrene. The binding agent may also contain a fluxing agent such as anthracene oil or pitch redistillate. The material to be briquetted may if dry be treated with a wetting agent such as gas condensate or it may be mixed with sulphite waste liquor, the sulphite waste liquor being mixed with the material either before or simultaneously with the tar pitch melt. In a modification the coal tar or coal tar pitch used for the production of the tar pitch melt may be partly or wholly replaced by other pitches which contain aromatic hydrocarbons, for example wash oil pitch or brown coal tar pitch. The materials which may be briquetted include dry ores and moist ores, e.g. iron ore, a mixture of chalk and iron ore, blast furnace dust, ore dust, blast furnace dust sludge, or flotation sludge, alone or in admixture with fuels, e.g. coke slack sludge, coke slack, coal sludge, coal or anthracite dust. The briquettes may be calcined and/or sintered when containing e.g. materials which are hydroxides or oxides of alkaline earth metals such as magnesium hydroxide or oxide, calcium hydroxide, sludge resulting from the production of acetylene from calcium carbide, or chalk. In an example a fine grain magnesium hydroxide containing 40 per cent of water is mixed with 7 per cent of a tar pitch melt consisting of 25 per cent of anthracene and 75 per cent of hard pitch blown with air is shaped and dried at 80 DEG C. The dried pieces are calcined and sintered in a kiln while raising the temperature up to about 1600 DEG C. Specifications 237,959 and 239,474 [both in Class 50] are referred to.