US3446614A - Production of iron alloys - Google Patents

Description

United States Patent US. Cl. 75129 3 Claims ABSTRACT OF THE DISCLOSURE A solid shaped composition for treating molten iron in a cupola, the composition containing 35 to 90 parts by Weight of an element capable of alloying with iron, such as ferrosilicon, 5 to 40 parts by weight of a fluxing agent such as calcium fluoride, and 5 to 20 parts by Weight of a binder such as portland cement.

This invention relates to the production of iron alloys.

It is normal practice when melting iron in a cupola to make additions of alloying elements to the molten metal. These additions are usually made because generally the iron originally put in the cupola will not, after being melted in the cupola, be of the type required. Alloying elements are therefore added to make up for any deficiencies in those' elements in the original charge and to give the final metal its desired properties. Fluxing agents are also to obtain a good separation of the metal from the slag, the added so as to produce clean metal from the cupola and fluxes also serve to prevent bridging in the cupola and the formation of what are known as slag curtains over the tuyeres.

Commonly used alloying elements include silicon, manganese, chromium and phosphorus and whilst some of these can be added in pure elemental state, they are generally added in the form of alloys, e.g. ferro alloys, as, for instance, ferro silicon and ferro manganese. Such alloys are generally added as tablets or briquettes.

The fluxing agents, e.g. mixtures of inorganic salts, are normally added as briquettes, the flux being tableted with a binder, and optionally also with a carrier. Preferably they are so compounded that decomposition of the briquette does not occur until it has reached the melting zone of the cupola whereby a more efl'icient fluxing action is obtained.

It has now been found that improved cupola additions, for alloying purposes, are obtained if the alloying element (or alloy thereof) is compounded with a fluixing material, the alloying element, or alloy thereof, constituting at least 50% by weight of the compounded mixture, e.g. tablet, briquette or the like. The tablet or briquette then serves the dual purpose of alloying and fluxing and it is found that, due to the presence of the fluxing agent, a more efficient pick up of the alloying element is achieved.

According to the present invention therefore a solid shaped composition for addition to molten iron comprises an element or alloy thereof capable of alloying with iron, a fiuxing material and a carrier or binder, the said element constituting at least 35% by weight of said composition.

According further to the present invention a method of treating molten iron comprises adding thereto a shaped solid composition as just set forth.

The use of such solid shaped compositions does not obviate the necessity of adding fluxing agents in the manner 3,446,614 Patented May 27, 1969 known per se, but the amount of such fiuxing additions can be substantially reduced when using the solid shaped compositions of the present invention. The said compositions provide a convenient and economic method of introduction of predetermined quantities of alloying additions to balance the charge.

Furthermore, the presence of the fluxing material ensures rapid melting of the composition when it reaches the melting zone of the cupola, thus providing at the right time and place the fluxing ingredients which give improved efficiency in pick-up of the alloying elements. Moreover it has been noted that a rapid separation of molten metal from the slag is achieved, which reduces the tendency for the metal to pick up sulphur.

Suitable shaped solid compositions, e.g. briquettes, according to the present invention may contain:

Parts by weight Alloying element or ferro alloy thereof (calculated as alloying element) 35-90 Flux (e.g. a fluoride or mixture of fluorides) Binder 5-20 If the binder is cement then up to 12 parts of water may be additionally included.

The following examples will serve to illustrate the invention:

EXAMPLE 1 The following ingredients are compounded and briquetted:

Parts by weight Alloying element (Si, Mn, Cr or P) or ferro alloy thereof 50 Calcium fluoride 23 Cement 18 Water 9 EXAMPLE 2 The following ingredients are compounded and briquetted:

Parts by weight Ferrosilicon (containing silicon, particle size 8 Briquettes of 2 /2 lb. Weight are prepared according to Example 1 or 2 using ferrosilicon and adjusted to contain approximately 40% by weight of silicon element.

These briquettes are used as a cupola addition for cast iron. In use, the briquettes should be charged so that they lie on top of the coke layer. When charges are small the briquettes should be thrown direct on to the coke layer in the cupola. When a mechanical drop-bottom charger is used with larger charges, the briquettes should be placed at the bottom of the charger; when a tilt charger is used the briquettes should be placed on top of the charge.

The number of briquettes used will be course depend on the amount of silicon it is desired to introduce into the charge. Considered per British ton of charge metal, each briquette will introduce approximately 0.045% of silicon. Thus, for example, to introduce 1% of silicon into a British ton charge of metal about 23 said briquettes will be necessary.

I claim as my invention:

1. A solid shaped composition for addition to molten iron, said composition consisting essentially of ferrosilicon, a fluxing agent, and portland cement as a binder, the proportion of ferrosilicon in said composition being at least 35% by weight of the said composition.

2. A composition according to claim 1 wherein the specified ingredients are present in the following proportions:

Parts by weight Ferrosilicon 35-90 Calcium fluoride 5-40 Portland cement 5-20 3. A process for the treatment of molten iron in a cupola which comprises adding thereto at least one unit of a solid shaped composition consisting essentially of ferro- 4 silicon, calcium fluoride as a fluXing agent and portland cement as a binder, the proportion of ferrosilicon in said composition being at least 35% by weight of the said composition.

References Cited UNITED STATES PATENTS 2,814,579 11/1957 Stringham 14826 2,900,490 8/1959 Petryck et al. 219137 3,104,996 9/1963 Boddey 14940 L. DEWAYNE RUTLEDGE, Primary Examiner.

J. E. LEGRU, Assistant Examiner.

US. Cl. X.R.