METHOD AND DEVICE FOR PROCESSING IRON SILICATE ROCK

Abstract

A method is used to process iron silicate rock. At least one component is at least partially removed from the iron silicate rock. At least one component that is different from iron is thus removed from the iron silicate rock. The processed iron silicate rock is used for the production of pig iron or steel. The device for utilizing the processed silicate rock is designed as a device for producing pig iron or steel.

Claims

1-11. (canceled)

12. A process for treating iron silicate rock, comprising the steps of: at least partly removing at least one constituent other than iron from the iron silicate rock; and using the treated iron silicate rock for producing pig iron or steel.

13. The process according to claim 12, wherein the iron silicate rock is treated in a liquid state.

14. The process according to claim 12, wherein the iron silicate rock is treated at a temperature of from about 1300 C. to 1600 C.

15. The process according to claim 12, including introducing a reducing agent.

16. The process according to claim 12, including carrying out the treatment in a plurality of stages.

17. The process according to claim 12, including introducing oxygen for at least part of the time during treatment.

18. The process according to claim 12, including carrying out the treatment within an electric furnace with bottom flushing.

19. An apparatus for treating iron silicate rock, comprising: a furnace that has a feed facility for a gas, the iron silicate rock being treated in the furnace.

20. An apparatus for processing treated iron silicate rock, wherein the apparatus is configured as a facility for producing pig iron or steel.

21. The apparatus according to claim 20, the facility is a blast furnace.

Description

[0045] Illustrative embodiments of the invention are schematically depicted in the drawings. The drawings show:

[0046] FIG. 1: a schematic flow diagram of the process,

[0047] FIG. 2: a table showing the specification of the starting material,

[0048] FIG. 3: a table showing the specification for the slag product from the process.

[0049] FIG. 1 shows a schematic depiction for carrying out the individual process steps. In particular, the process sequence in the deep reduction of iron silicate rock to give a fayalite or magnetite product as raw material for use in the iron and steel industry is depicted.

[0050] The slag from the primary copper process is preferably introduced in liquid form into the deep reduction process. The liquid slag preferably has a temperature in the range from 1200 C. to 1350 C. A temperature value of about 1260 C. is typical.

[0051] As an alternative, working up slag heaps by the process of the invention is also envisaged. However, compared to processing of liquid slag, this involves a higher energy consumption since melting of the solid material is firstly required. A typical analysis of the starting material is shown in the table in FIG. 2.

[0052] The objective of the process is to separate the more noble metals of value present from the iron by selective reduction. The iron remains, bound to silicon and/or to oxygen as fayalite product (Fe.sub.2SiO.sub.4) or magnetite product (Fe.sub.3O.sub.4), for further use as starting material in the iron and steel industry. This product contains further oxides of Ca, Mg or Cr as impurities. The specification for the product is shown in the table in FIG. 3.

[0053] During heating to the preferred process temperature of 1400 C., the residual sulfur present has to be removed from the system by introduction of oxygen in order for the subsequent reduction period to be able to be carried out efficiently. The melt bath is covered and protected from further contact with oxygen by addition of not more than 7% of solid carbon, based on the amount of slag. The CO/CO.sub.2 ratio of the process atmosphere should be set so that an oxygen potential of 10.sup.12 atm is not exceeded. In this phase, the volatile constituents of the slag vaporize and leave the process together with the offgas. In the course of the offgas treatment, these constituents are obtained in the form of their oxides as fly dust. The fly dust obtained has a composition of about 40-60% of Zn, 10-20% of Pb and <10% of As and can be used as raw material for zinc production, e.g. in the rolling process. In the example shown here with an annual tonnage of 700 000 t, an amount of fly dust of about 20 000 t is to be expected.

[0054] The copper content after this process step is still about 0.2-0.3% of Cu. To separate copper and iron selectively, carbon monoxide is introduced as reducing agent via flushing bricks arranged at the bottom. The advantage of bottom flushing is the significantly lower gas velocity required compared to flushing by means of a lance. This leads to intensive mixing between slag, metal and gas phase. The reduction takes place at the gas/slag phase interface according to the reaction equation Cu.sub.2O+CO.fwdarw.2Cu+CO.sub.2. The metal droplets formed are very fine (max. 20 m) and have to be separated from the slag phase by density separation in a calming zone.

[0055] Depending on the further processing route, the mineralogy of the slag product can be matched to the respective use. If the product is, for example, to be used directly in a blast furnace, the fayalite phase obtained is satisfactory. For introduction via the blast furnace charger, pretreatment in the sintering plant is necessary. The melting range of fayalite (about 1180) is too low for this and would lead to problems in processing. It is therefore necessary to set the magnetite content in the finished product. This ratio can be adjusted according to the requirements of the customer by addition of a defined amount of oxygen. The oxygen can be added not only in the form of oxygen gas but also in the form of intermediates which serve as oxygen donors, e.g. Fe.sub.2O.sub.3 dust from the steel industry.