Abstract: A polymeric silicate material having a substantially fibre- or flake-like microstructure is manufactured from a starting material comprising mainly natural or synthetic silicate mineral e.g., Olivine and/or Granate (garnet), having a hardness exceeding the value 6 on the Moh's hardness scale and which are compound(s) having the general formulae:2(R.sup.I O).multidot.SiO.sub.2wherein R.sup.I may be the same or different and is Mg and/or Fe; and3(R.sup.II O).multidot.R.sub.2.sup.III O.sub.3 .multidot.3 SiO.sub.2wherein R.sup.II may be the same or different and is Mg, Fe and/or Ca; and R.sup.III is Al or Fe, by finely dividing said material to a specific surface area of at least 15,000 cm.sup.2 /cm.sup.3, measured according to Blaine, and subsequently hydrothermally treating the resultant powderous starting material at a temperature of approximately 175.degree.-325.degree. C. and a pH of at least 9 in the presence of water or condensed steam.

Abstract: Steam curable agglomerates of particulate material are cured by passing steam at elevated temperature and pressure through a bed of such agglomerates in an autoclave. The flow direction of the steam through the bed is periodically reversed, at least during the temperature raising period of the autoclaving process, to reduce the autoclaving time and produce cured agglomerates of substantially uniform quality.

Abstract: Gas bearing particles is cleaned by bringing it together with a friction-electrically charged mist of water droplets, which is formed by the aid of an electrically conducting liquid mist generating nozzle to which water in liquid state which has been de-ionized to a conductivity of at most about 1 .times. 10.sup.-5 ohm.sup.-1 cm.sup.-1, is supplied. From this nozzle the charge of a polarity opposite to that of the mist is continuously conducted away.

Abstract: Magnesia is recovered from scrap lining material rich in magnesia by leach treatment of the material with water in the presence of carbon dioxide under pressure, separating the leaching solution from solid leaching residues, precipitating out magnesium hydrocarbonates from the leaching solution and calcining the precipitate to form magnesia. To make the scrap lining material more readily leachable and enable the production of a rich leaching solution said lining material, prior to the leaching treatment, is treated with steam at a temperature within the range of 100 - 300.degree. C. and corresponding saturation pressures for a period of 1 - 50 hours.

Abstract: A starting material for the manufacture of shaped and hydrothermally hardened products is composed of a binding agent comprising finely-divided olivine having a specific outer surface of at least 25 000 cm.sup.2 /cm.sup.3, measured according to the permeability method, and finely-divided silica material in a quantity which is at most equal to the solid volume of said olivine and a ballast material in an amount of 50 - 80% by volume of the starting material and comprising particulate ultra-basic rock or slag material having a particle size of 80% smaller than 200 - 1000 .mu.m.