Published: April 1978
Titanium dioxide is the leading white pigment, with a world output of about 1.75 million metric tons/yr. It is produced by two methods: the chloride process and the sulfate process. The object of this study is to compare the technology and economics of these processes and to evaluate the disposal or reuse of chloride and sulfuric acid wastes.
Two versions of the chloride processes are considered--one using rutile (95% TiO2) and one using enriched ilmenite (70% TiO2), a mixture of ilmenite, leucoxene, and rutile ores, The rutile-fed process of Sec tion 5 is patterned, so far as possible, on Tioxide International technology. This was done because of the appreciable body of Tioxide patents and related information. The mixed-feed process of Section 6 follows Du Pont practice both because of the volume of patent literature and because DuPont's is the only commercial chloride operation using the lower purity feed. The authors have no inside information from either Tioxide or DuPont; thus, there is no assurance that the processes evaluated in this study are identical to those used by Tioxide and DuPont.
Section 5 considers the technology of all companies other than DuPont that use a rutile feed. Section 6 is limited, so far as possible, to DuPont practice. However, in many cases, operations are interchange- able and an optimum process design would probably incorporate features from several companies. Both processes evaluated are divided into chlorination and oxidation plants to enable handling of the numerous plant sections in the PEPCOST computer program.
The sulfate process evaluated in Section 7 uses a conventional ilmenite feed (55% Ti02) and a technology which is not intentionally representative of any one company's operation. The process evaluated in Section 8 uses the same technology on an upgraded titaniferous slag (85% TiO2) This slag was selected as a raw material for evaluation because a plant to produce it will come onstream in 1978.
Section 9 deals with alternative, but untested schemes, for TiO2 pigment production, and Section 10, with the problems and economics of waste disposal or reuse.
The hypothetical plants evaluated in this study are located on the U.S. Gulf Coast. However, the economics are also believed to be applicable to the Atlantic Coast, which is more advantageous relative to U.S. pigment markets.