Vacuum Smelting Process for Producing Ferrotungsten-Description VIII

During the vacuum smelting operation, other constituents which are also volatilized and removed from the pelletized feed stock to effect a purification of the resultant ferrotungsten alloy residue include: silica, iron and iron compounds, calcium compounds, manganese and manganese compounds, aluminum compounds, lead compounds and other oxygen-containing compounds, as well as other conventional impurities normally found in ore deposits containing tungsten. The substantial reduction in the content of such contaminating constituents renders the resultant ferrotungsten alloy briquettes eminently suitable in many instances for direct use as metallurgical alloying agents in steel-making operations and the like without any further purification. A typical composition of ferrotungsten alloys, including permissible amounts of various contaminating constituents in accordance with ASTM specifications are as follows:

______________________________________

Tungsten 72.0 - 82.0% Carbon 0.60 max. Phosphorous 0.060 max. Sulfur 0.060 max. Silicon 1.00 max. Manganese 0.75 max. Copper 0.10 max. Arsenic 0.10 max. Antimoney 0.080 max. Tin 0.10 max. Total arsenic, antimony and tin 0.20 max. Iron Balance

______________________________________

The ferrotungsten pellets produced can be suitably packaged in steel containers providing premeasured quantities of the ferrotungsten alloy, and in that form can be utilized in steel-making and foundry operations.

The temperature of the pelletized feed stock during the vacuum smelting operation may range from as low as about 2500° F. to as high as about 3100° F. and preferably is controlled within a range of from about 2700° F. to about 2900° F. Temperatures below about 2500° F. are commercially unsatisfactory due to the slow rate of reduction of the tungsten oxide constituent, while on the other hand, temperatures above about 3100° F. are undesirable because of excessive costs of refractories required in the vacuum smelting furnace. The vacuum smelting operation is carried out at pressures less than about 0.5 Torr and preferably at pressures less than about 0.05 Torr (50 microns) to as low as about 0.001 Torr (1 micron) and even lower, depending upon the limitations of the vacuum equipment employed. Particularly satisfactory results are achieved when the pelletized charge is heated at a temperature ranging from about 2800° F. to about 3100° F. employing a vacuum ranging from about 0.05 Torr to about 0.001 Torr.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

• < Prev
• Next >