Economic Evaluation for the Production of Sorbents and Catalysts Derived from Hydrous Titanium Oxide Microspheres Prepared by the HMTA Internal Gelation Process

Abstract

Hydrous metal oxides of Zr, Ti, Hf, Fe, Al, etc. are inorganic ion exchangers that have high selectivities and efficiencies for separating and removing fission products, actinides, and other undesirable elements from aqueous waste streams. In most cases, these ion exchangers are commercially available only as fine powders or as unstable granular particles that are not readily adaptable to continuous processing techniques such as column chromatography. Hydrous metal oxides can be prepared as microspheres by the internal gelation process. This process is unique in that it provides a means of making a usable engineered form of inorganic ion exchanger that can be used in large-scale column separations. With such material, the flow dynamics in column operations would be greatly enhanced. In addition, the microspheres are in a stable form that has little or no tendency to degrade under dynamic conditions. Another advantage of the process is that the gelation time and size of the microspheres can be controlled. Also, microspheres can be reproducibly prepared on either a small or a large scale-which is not always true for batch preparation of the powdered or granular forms. The use of these materials can be expanded in a number of ways. The process allows for the microspheres to be homogeneously embedded with fine particles of other selective ion exchangers, and for the microspheres (undried) to be chemically converted to microspheres of other ion-exchanger materials such as phosphates, silicophosphates, hexacyanoferrates, tungstates, and molybdates. This report presents an economic evaluation of the preparation of hydrous titanium oxide (HTiO) microspheres by an internal gelation process for use in making ion exchangers, catalysts, and getters. It also examines the estimated costs for a company to produce the material but does not discuss the price to be charged since that value would take into account company policy-matters that cannot be covered here. Since the volume of business is not known, the costs were bracketed between the laboratory-scale system of making 1 to 2 lb HTiO/d of dried beads per 8-h day and a small pilot-scale system of producing 1 to 2.4 lb HTiO/h. The best estimates were between $286 and $534 for the laboratory-scale production of 520 and 260 lb/year, respectively, and between $93 and $107 for the pilot-scale production of 1.5 tons/year. The costs of producing microspheres in a pilot-scale facility will be strongly dependent on the scale of the facility and the fraction of time it is used. The preparation of inorganic materials as microspheres has the potential for many additional applications. If these applications prove to be feasible, the cost of producing the materials could be decreased even further.