Materials Week '97: Monday PM Session

Focusing on physical metallurgy and materials, Materials Week '97, which incorporates the TMS Fall Meeting, features a wide array of technical symposia sponsored by The Minerals, Metals & Materials Society (TMS) and ASM International. The meeting will be held September 14-18 in Indianapolis, Indiana. The following session will be held Monday afternoon, September 15.

TITANIUM EXTRACTION AND PROCESSING: Session II: Processing of TiO₂ and TiCl₄

Sponsored by: LMD Reactive Metals Committee

Program Organizers: B. Mishra, Dept. of Metal. & Matls. Eng., Colorado School of Mines, Golden, CO 80401; G.J. Kipouros, Dept. of Mining & Metall. Engg., Technical Univ. of Nova Scotia, Halifax, Nova Scotia,Canada B3J 2X4; J. Monsees, International Titanium Association, 1871 Folsom St., Suite # 100, Boulder, CO 80302; S. Daniel, Oremet Titanium, 530 W. 34th Avenue, P.O. Box 580, Albany, OR 97321

Room: 203

Session Chairs: Dr. R.G. Reddy, Department of Chemical and Metallurgical Engineering, MS 170, University of Nevada, Reno, NV 89557; Dr. J.N. Hryn, Argonne National Laboratory, 9700 S. Cass Avenue, Bldg. 362, Argonne, IL 60439-4815

WASTE METAL CHLORIDE PROCESSING AND CHLORINE RECYCLE: J.W. Reeves and R.G. Reeves, 3R Associates, 8 Wollaston Road, Wilmington, DE 19810

In the chlorination of titania ores to produce titanium tetrachloride, all minerals present are chlorinated except silica. These anhydrous chlorides are waste products that must be processed for disposal, recycle or sale. The ores chlorinated range in titania content from 50% to 96% with a resulting wide range of waste to be processed. More than 60% of the titania ores chlorinated are 85% titania or less and a large portion of this is less than 65% titania. Currently, none of the chlorine in this waste is recycled, less than 10% is processed for sale and the remainder is either treated for disposal, pumped into deepwells or dispersed into the sea. While there has been extensive research on chlorine recycle, no process has been found with sufficient economic potential. Instead, titanium tetrachloride producers have chosen to purchase higher titania ores when their additional cost is less than the waste processing cost. The metal chloride oxidation technology will be reviewed as well as chlorine recycled by other means such as electrolysis and pyrohydrolysis. Disposal technologies by neutralization and deepwell disposal that are currently practiced will be reviewed also. The prospects for improved chlorine recycle processes versus high grade ore cost will be discussed.

2:40 pm

NEW OPPORTUNITIES FOR THE TREATMENT OF CHLORIDE CONTAINING BY-PRODUCTS FROM THE TITANIUM PRIMARY INDUSTRY THROUGH PYROHYDROLYSIS: C. Kogler, F. Barhold, Process Development Division, Keramchemie GmbH, Postfach 1163, D-56425 Siershahn, Germany

During processing of different raw materials in the titanium/titaniumdioxide industry a lot of undesirable by-products can occur. One example is the production of synthetic rutile out of ilmenite. This titanium ore can be treated by leaching, to separate the rutile from accompanying elements. Through the leaching step a chloride solution with varying Fe, Mg, Al, etc. contents is produced. This waste liquid can be heated very efficiently by pyrohydrolysis in a fluidized bed reactor. The products are a regenerated acid and granular metal oxides. Pyrohydrolysis in fluidized bed reactors is a well known technology for the treatment of used pickling acids in the steel industry. The applicability of this technology for the titanium industry is addressed in this paper. Pilot plant trials have been carried out on different by-products of the titanium producers (solutions and slurries). Conclusions on how production plants for the treatment of those wastes can be operated are drawn from the results.

3:05 pm

REMOVAL OF IRON FROM MIXTURES OF IRON-TITANIUM OXIDES USING CARBOCHLO-RINATION PROCESS: F.C. Gennari, A.E. Bohe, D.M. Pasquevich, Centro Atomico Bariloche, CNEA, CONICET, 8400 Rio Negro, Argentina

Chlorination in the presence of carbon, carbochlorination, is considered one of the most attractive methods to separate metals, as chlorides, from low-grade polymetallic minerals. The carbochlorination of iron-titanium oxides mixtures was studied in the temperature range of 600 to 950°C using thermogravimetric measurements (TGA), XRD, SEM, EDS, chemical and neutronic activation analysis. The effect of kinetic variables, such as reaction temperature, chlorine flow rate, mass transfer in the solid bed and the iron-titanium oxides ratio, on the iron removal was investigated. It was found that iron quantitative separation occurs at low temperature. The carbochlorination showed the existence of different reaction stages which are strongly dependent on experimental conditions. Interactions between iron and titanium chlorides with the starting oxides were also observed, giving rise to an alteration of the mixture reactivity as a function of reaction conversion.

3:30 pm BREAK

3:45 pm

THE SCHEME OF PIGMENTARY TITANIUM DIOXIDE PRODUCTION BASED ON THE ORES OF TITANIUM-MAGNETITE ROCK DEPOSITS: N.A. Vatolin, L.I. Leontiev, S.V. Shavrin, Institute of Metallurgy, Ural's Division of Russian Academy of Sciences, 101 Amundsen Str., Yekaterinburg 620016, Russia

The usage of rock ores gives a rise to ecologic problems including much difficulties associated with the waste materials utilization. Technical solution of such problems depends on the character of ilmenite and titanium-magnetite dissemination in the ore and on their mutual inosculation with each other. The scheme of concentration of the ore containing from 7 to 17% of titanium dioxide was developed. This scheme eliminates the stage of flotation and provides for complete utilization of the waste materials in the forms of gravel. building sand and aggloporite. The economic efficiency is conditioned by obtaining of two merchantable high-grade concentrates - the iron-vanadium concentrate with 60-65% of iron and 0.8-1.1% of vanadium pentoxide and the ilmenite one with 42.5-45.0% of titanium dioxide. The total yield of concentrates depends on the ore's composition and structure and varies between 20-51%. The iron-vanadium concentrate is utilized by vanadium-making industry and the ilmenite one is used after special pretreatment for smelting of titanium slags. The pretreatment includes pelletization or pelletization and metallization. In the second case besides the melting in electric furnaces some more ways are considered providing for coagulation of the metal with it following extraction up to 90% by magnetic separation. The main attention in pigmentary titanium dioxide production is paid to its quality. The latter corresponds to the international quality standards requirements.

4:10 pm

SELECTIVE DISSOLUTION KINETICS OF THE ILMENITE: Z. Jin, L. Wang, Z. Duan, Department of Metal Materials, Chengdu University of Science & Technology, Chengdu, China 610065

Sichuan province in China is endowed with abundant Ilmenite resources. Because of the low titanium content and high magnesium-calcium inpurity, it was difficult to yield commercially acceptable product from the ilmenite using general benefication method. This investigation has demostracted an effective way to select dissolve ferrous ion from the Ilmenite in dilute hydrochloric acid and to produce artificial rutile containing 90% TiO₂. The kinetics of selective dissolution reaction was studied. The effects of stirring, temperature, particle size, HCl concentration were investigated. The results indicated that the selective dissolution reaction was topochemical and fit a surface reaction control model. The activation energy was calculated to be 56.94 KJ/mol. The order of the reaction rate are 2 with respect to HCl concentration. It was found that a small amount of phosphoric content in the ilmenite would significantly decrease the selective dissolution rate. And a mechanism of selective dissolution ferrous ion from ilmenite was proposed.

4:35 pm

LOW TEMPERATURE TiO₂ PRODUCTION PROCESS: L.D. Smillie, M. Heydenrych, Mattek- CSIR, Division of Materials Science & Technology, P.O. Box 395, Pretoria 0001, South Africa

A unique process has been developed for selective chlorination of low-grade titanium-containing ores. The ore is first treated by carbo-thermal reduction in which the titanium component of the ore selectively forms a carbo-nitride. This species chlorinates at far lower temperatures (typically 350°C) than the conventional high-temperature chlorination process. The other oxides are unreactive at these temperatures - a relatively pure titanium tetrachloride product can be obtained in the low-temperature chlorination. The carbo-thermally reduced ore can be produced at a cost that is competitive with conventional feedstocks on a weight-for-weight basis of titanium. Low-temperature chlorination also presents many opportunities for cost reduction over the existing processes. The remaining unchlorinated ore is not environmentally harmful - the selectivity of this process gives it an edge over the existing processes in terms of environmental impact because unwanted oxides are not chlorinated.