barium silicate is a white to pale green, orthorhombic mineral that occurs in nature as the natural silicate of barium, Ba(SiO2). It is a common material used in paper coatings and in cellulose-based materials such as regenerated cellulose. In addition, it is found in a variety of industrial applications as a “getter,” or unwanted gas remover for vacuum tubes and as an alloying ingredient in load-bearing cast irons and steels.

The object of the present invention is to develop a process that enables commercial production of water leachable barium silicate in continuous furnacing equipment such as a rotary kiln without contamination by sintering or fusion and that achieves high conversion. It is also an object of the present invention to produce such a product in high yields with minimal consumption of kiln fuel and to utilize low cost raw materials such as barite, silica flour, and gypsum.

A critical factor in achieving the above objectives is to provide a controllable slightly reducing atmosphere within the kiln which results in only very small amounts, less than 0.5%, of barium sulfide being formed in the kiln reaction product. This is accomplished by providing a low sintering temperature and by using a barium to silicon ratio of the kiln feed material of from 2.5 to 1 as compared to the conventional silica to silicate feed.

Another critical element is the refractory lining of the rotary kiln which must be designed to resist the decomposition reactions. This is achieved by using a fire clay refractory containing 40% to 90% alumina. The refractory can be reinforced with sillimanite or stevensite. A bleed of the recycled leach residue is required to maintain the Fe O content of the kiln feed below 2%.