A preliminary economic analysis has indicated that the making of acetylene, via a kiln calcium carbide process, can be cost competitive with ethylene if used to produce vinyl chloride monomer. The work presented here includes (1) the kinetics of carbide formation from reduction of lime, (2) the characterization of this carbide product, and (3) a process demonstration in a prototype bench-scale rotary kiln. From the study of the reduction chemistry, it was found that reduction rates of lime to carbide are fast, needing less than 30 min to achieve conversions of 50-80% (1740-1870 °C). An increase of carbon monoxide pressure in the surrounding atmosphere tends to inhibit the reaction.

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A new process for the manufacture of technical-grade phosphoric acid uses fossil fuel as an energy source rather than electric power. Phosphate ore in a conventional direct-fired rotary kiln is reduced with carbon to elemental phosphorus. Burning of the phosphorus and co-produced carbon monoxide provides energy for the endothermic reduction. The process has been demonstrated in a 10 tons/day solids feed capacity pilot kHn, obtaining phosphate

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