Abstract: A method for producing a porous magnesia clinker by admixing a magnesia material having a grain size of less than 0.1 mm with from 10 to 60 percent by weight of the mixture of fluid oil coke having a grain size of 1 mm or less, calcining the resulting mixture at a temperature of from 900.degree. to 1600.degree. C. for a time sufficient to burn off the coke and thereby to form pores in the magnesia material, and firing the resulting product at a temperature of from 1600.degree. C. to 2030.degree. C. to produce porous magnesia clinker.

Abstract: A hardened product prepared by mixing cement with limestone or dolomite and hardening it by incorporating water can be used as a heat medium for a fluidized bed heating furnace and also act as a preferred desulfurizing agent having a high desulfurizing performance which can effectively absorb to eliminate the sulfur components in exhaust or product gases from the heating furnace.The strength as the heat medium and the desulfurizing performance can further be increased by setting the cement content in the mixture between 10-70% by weight and the particle size for the mixture between 0.7 and 2.0 mm.Furthermore, the desulfurizing agent can be produced preferably by previously setting the particle size of the mixture to less than 0.3 mm and then adding 5-20% by weight of the seed material between 0.3 mm and 1.2 mm in particle size, followed by pelletization.