Sponge blasting

Surface preparation typically takes place concurrently with joint termination demolition. Surface preparation can be performed by ultra-high-pressure water blasting, abrasive blasting, or pneumatic sponge blasting. 

CA 65, 8559(1966) (A novel expl compn suitable for blasting consists of a rod of A1 sponge 1 inch diam x 1 ft long which is wrapped in Al foil so as to enclose one end and the circumference. A suspension of 20 wt % channel black in liquid O is poured into the open end of the foil container to achieve absorption of O by the sponged Al. After inserting ail electric detonator, the open end is sealed with Al foil and the ensemble kept in liq O prior to insertion into a borehole in rock. Detonation shatters the rock evenly, producing considerable heat, but little smoke)... 

Electric smelter i Blast lurnace Shah furnace Sponge iron... 

One of the more important alternatives to the blast furnace for the production of iron is direct reduction of pelletised ore in a shaft reactor. The reducing gas mixture is usually obtained by steam reforming of natural gas and flows upward,countercurrent to the downward flow of solids. Sponge iron obtained by direct reduction may be used directly in arc furnaces for steel production. 

Direct reduction of iron ore to sponge iron which can then be converted to steel in an electric arc furnace is a process that takes place outside a blast furnace avoiding the use of coke. This process is more favorable than the traditional raw iron production by merms of coke. The chemical reactions are ... 

Iron oxide also can be reduced in a direct reduction furnace, which operates at much lower temperatures (1300-2000°F) than a blast furnace and produces a solid "sponge iron" rather than molten Iron. Because of the milder reaction conditions, the direct reduction furnace requires a higher grade of iron ore (with fewer impurities) than that used in a blast furnace. The iron from the direct reduction furnace is called DRI (directly reduced iron) and contains —95% iron, with the balance mainly silica and alumina. 

The coke must be strong enough to resist the weight of overburden in the blast furnace, which is why coking coal is so important in making steel by the conventional route. However, the alternative route to is direct reduced iron, where any carbonaceous fuel can be used to make sponge or pelletized iron. 

In the 1960s the A. O. Smith Company in the United States introduced a new method for the development of powdered metal, called water atomization. In this method, the pure metal is melted and a small stream of the liquid is allowed to flow from the bottom of the container of molten metal. A high-pressure blast of cold water hits the stream of metal, breaking it into small droplets that quickly solidify. Powdered metal particles made in this way are more smooth and dense than the sponge powder particles from oxide scrap. In addition to powdered iron metal, many copper, bronze, carbide, and brass parts are made through powder metallurgical processes. 

Methanol is used in the steel industry [97]. Methanol has been proposed as a synthesis source in the direct reduction of iron or to sponge iron (containing 90% of Fe) by removing most of the oxygen at a temperature of about 850 C. Molten iron is not produced in this process but is formed in the conventional blast fiirnace route of iron core reduction. This process has ined popularity because it requires a smaller capital investment and produces a superior quality product than the traditional blast fixmace route. Currently, natural gas is the primary reductant used, but methanol is considered when coal, natural s, or fuel oil is not readify available at the iron ore mine mouth. 

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