HRP921490A2 - Dry cold process for making foundry dusts into briquettes - Google Patents

Description

The technical field to which the invention belongs

The invention relates to a process for cold briquetting of smelter dusts and belongs to the field of casting.

Technical problem

The technical problem that is solved by the described invention is contained in the following: how to implement a process for cold briquetting of cast iron dust that will eliminate the shortcomings of the hitherto known processes and with which it will be possible to reuse steel dust in converters, for example for this occasion?

State of the art

During a series of metallurgical processes in smelters, metal dust is created. Thus, for example, during the production of steel by the well-known process of oxygen blowing, appropriate steel dust is created, which is collected by suitable filters. The dust has a high metal content and, depending on the process, iron is available in the form of metal or oxide.

The processing of this type of dust always presents a difficulty in terms of environmental protection and associated costs. Its high metal content is suitable for the reuse of dust, and thus the attempt to return this dust to the steelmaking process was not missed.

Dusts with a high metal content, mainly parts of pyrophoric iron, are briquetted with the help of the hot briquetting process and returned to the converter. Methods of blowing dust into converters as well as the granulation process with the addition of binding material are also known. With the mentioned methods, materials that are not suitable for the metallurgical process reach the converter. Thus, the process of US-A 833 630 describes the briquetting of brittle ores, whereby the addition of special limestone in a mixture with magnesium and portland cement proved to be significant, because sufficient strength of the ore briquettes cannot be obtained in any other way. The moisture found in the ore from 18 to 20% is of particular importance for the hydraulic reaction with the Portland cement binder. In this known briquetting process, the required strength of the ore briquettes was achieved using the Portland cement reaction.

A similar procedure is described in DE-B 1 142 442. In this document, the procedure is in the briquetting of fine ores. For the briquetting of fine ores, the basic additional material used, especially magnesium hydrate and/or calcium hydrate, is a binding agent, which reacts with carbon dioxide from the air into carbonate and thus ensures the required strength of the briquettes.

Also during other metallurgical processes, during the production of electrical steel or in the aluminum industry, smelting dust is obtained, which requires removal or, if possible, return to the process.

Description of the solution to the technical problem

The technical problem was solved by this invention in such a way that the dust at pressures over 10,000 bar at a normal temperature of 30° C together with calcium, dolomite, magnesium, dunite, olivine or bauxite in burned or unburned form always by themselves or in mutual the mixture is briquetted into briquettes that are pulverized and suitable for transport.

With the help of the process according to the invention, smelter dust, especially blowing dust, at a normal temperature of 20°C with the application of high pressures of over 10,000 bar, can be converted into transportable briquettes by adding basic additives. These briquettes can be brought back into the process of obtaining steel in a form that does not pollute the environment, while utilizing the material they contain. The process according to the invention, that of dry briquetting, simultaneously with the removal of dust from smelters, solves hitherto indistinguishable problems of environmental protection. As a special advantage, the fact that the process according to the invention is carried out does not burden the environment through harmful factors from the waste gases of organic or inorganic binders.

Limestone, dolomite, magnesite, dunite, olivine, bauxite in burnt or unburnt form are introduced as an additional material of the briquetting process according to the procedure, which on the one hand enables the briquetting of smelter dust, especially blowing dust, and on the other hand positively affects the fresh process. always alone or in mixtures. Special advantages are shown, when carrying out the process according to the invention, by adding 50 parts by weight of limestone to the dust from blowing for every 100 parts by weight of dust and this mixture is subjected to cold briquetting using high pressure presses.

According to a further embodiment of the invention, 40 parts by weight of calcined limestone, 5 parts by weight of sinterdunite and 5 parts by weight of calcined bauxite can be added to the steel dust from blowing, for every 100 parts by weight of dust.

Only by means of the method according to the invention it became possible to solve the above-mentioned problems in accordance with the purpose. If you try to shape the steel dust from blowing on presses or ring presses into briquettes, you will not get shapes that are permanent. The steel dust in blowing has an extreme fineness (100% smaller grains than 20 //m) and is a liquid dust like water, so that only in addition to extreme pressures over 10,000 bar, as foreseen by this process according to the invention, at normal temperature and with the addition basic materials, they can dry briquettes suitable for transport and which do not dust.

The procedure according to the invention will be explained in more detail in the following examples:

Example 1:

500 tons of steel dust from blowing from the Ldkonvertor is taken through a Lurgi dedusting device and with the addition of 40 weight units of calcined limestone, 6 weight units of sinterdunite and five weight units of baked bauxite to every hundredth part of the steel dust is briquetted at 12,000 to 15,000 bar in high pressure presses. pressure at normal temperature.

Briquettes that are suitable for transport and do not dust can be fed back to the LD converter with the usual dosing means.

Example 2:

100 tons of dust from the aluminum industry are briquetted with the addition of 10 parts by weight of limestone and five parts by weight of sinterdunite for every hundred parts by weight of dust, at normal temperature under a pressure of 10,000 bar. The created dust in the form of pieces can further be used in the smelting industry.

Example 3:

200 tons of dust obtained from an electrical steel smelter is pressed into briquettes with 10 parts by weight of limestone and five parts by weight of sinterdunite for every hundred parts by weight of dust, at normal temperature and under a pressure of 10,000 bar. The obtained briquettes, suitable for transport, can be brought back to the process of obtaining electrical steel or to the process of non-ferrous metals - smelters.

Claims (3)

1. Dry process for cold briquetting of smelter dusts, under high pressure and with the addition of basic additional materials, characterized by the fact that the dust at a pressure of over 10,000 bar and a normal temperature of 20° C, together with limestone, dolomite, magnesite, dunite, with olivine or bauxite, always in baked or unbaked form and alone or in a mixture, they are shaped into briquettes that do not dust and are suitable for transport. 2. The method according to claim 1, indicated by the fact that the steel dust obtained by blowing with the addition of 50 weight units of limestone for every hundredth part by weight of the dust is formed into briquettes. 3. The method according to claim 1, indicated by the fact that steel dust with 40 parts by weight of calcined limestone, 5 parts by weight of sinterdunite and 5 parts by weight of calcined bauxite, for every hundredth part by weight of the dust, is formed into briquettes.