DE1210019B - Process for the extraction of pure iron and / or iron oxide by halide metallurgy - Google Patents

Description

Process for the extraction of pure iron and / or iron oxide on halide metallurgy Way The invention described in the main patent 1136 722 relates to a method for Extraction of pure iron and / or iron oxide by means of a halide metallurgical process Process in which finely ground coke, finely ground coke, in several process steps ferrous ore, dusty gangue and Fe203 dust with chlorine or a mixture reacted by gaseous chlorides and nitrogen and reducing gases in order to finally obtain pure iron.

Various methods and devices already exist for such purposes.

Systems are known, consisting of several containers that hold the solids contained, through which a gas flows. This is done according to the cascade principle the solid from the first to the last and the gas from the last to the first Container transported. These procedures are cumbersome, and the facilities have Relatively small throughputs compared to their size. In addition, the The flow velocity of the gases in the containers does not exceed a certain level, because otherwise solid particles will be carried away in unacceptably large quantities.

Also in rotary kilns, in which solids are continuously mixed with gases brings into contact in countercurrent, the flow velocity of the gases must not be so big that a lot of dust is carried away. If, for example, a chemical Process (e.g. ore reduction) or a physical process (e.g. drying or Heating a finely ground solid) for treating the solid proportionately a lot of gas is required, the rotary kiln must have a very large clearance, so that the flow velocity of the gas is sufficiently small.

When adding heat in endothermic processes or during extraction of waste heat in exothermic reactions are the heat transfers in the containers and Rotary kilns bad; the heat losses are great because the required Residence times of the solids in these apparatus are long.

The multi-stage fluidized bed processes allow excellent Heat transfer between gas and solid, however, the fluidized bed towers must also often have large clearances so that the flow velocity of the gases is just that Create a vortex and do not carry the solid up. In addition, are in fluidized bed processes the fluctuations in the flow rate of the gas are set very narrow limits.

In the above-mentioned processes, the content of the finest Dust in the solids should be as small as possible, so that no large dust losses and no expensive dedusting devices are required.

To transfer heat between gases and solids, one operates sometimes the principle of pneumatic conveying. Gas and solid become mixed together and blown through a pipe, being highly turbulent as a result Currents transfer heat very quickly from one phase to the other will. But since both components are brought into contact with each other in direct current and are moved, only an average mixing temperature can be achieved, i. H., much less heat is transferred than when using the countercurrent principle.

Methods and devices for separating solids are known from gases (cyclones). These devices are used exclusively for the separation of Phases (solid-gaseous or solid-liquid) are used. The phase mixture flows in enters the cyclone, is separated in it, and each phase leaves the cyclone for itself alone. To improve the separation effect, several cyclones are also connected in series (Fig. 1). The solids content of the mixture takes from cyclone to cyclone down; the non-separated solid and the gas pass. all Cyclones together, i.e. in direct current.

It is also known to use cyclones in the dedusting of hot gases to be used with double jackets through which a cold medium flows - to control the gases cool or to avoid scaling of the metallic Zyllon walls (cooling cyclones). For some purposes, e.g. B. for cyclone burners, one uses cyclone-like devices, the inside one. Have heat-resistant lining that is made from cooling tubes existing jacket is surrounded, which is thermally insulated to the outside and by a sheet metal jacket is surrounded.

The purpose of the present invention is to avoid the shortcomings of the above-mentioned processes in the production of pure iron and / or iron oxide according to patent 1,136,722. Gases or vapors are vigorously mixed with granular, fine-grained or dust-like substances according to the countercurrent principle and brought into action continuously. The mixtures can be quickly heated or cooled; heat losses are negligibly small. Because dust-fine solids are used and, as a result of the known self-grinding of the dust, new, highly reactive surfaces are constantly created on the solid particles, the reaction rates are high and, as a result, the required reaction times are surprisingly short. The throughput of the requests is very high compared to their dimensions.

Such devices ("cyclone batteries") have been proposed for other purposes and have been in practical use in industry for several years. Their use in the halide metallurgical extraction of iron or iron oxide according to patent 1136 722 is new.

The method is based in principle on the fact that dedusting devices themselves used as reaction chambers and connected to one another in such a way that in the plant chemical and / or physical processes according to the countercurrent principle and at the same time separation processes take place in the individual devices.

The gases (Fig. 2) are passed through several cyclones in one direction and the solids passed through in the opposite direction. The fresh gas. comes with the one leaving the device: solid before and in the last Cyclone in contact; the exhaust gas meets the fresh one entering the device Solids together in the first cyclone.

This is where the solids separated from the individual cyclones become z. B. by. Conveyor screws from the solids discharge opening of one cyclone to the Inflow opening of the next cyclone promoted. However, it is particularly advantageous if the solid immediately after leaving a cyclone of the. from the next one Cyclone coming gas flow detected and mixed with this in the intermediate Cyclone is promoted.

If only two cyclones are used, the solids will be immediate after leaving the first cyclone immediately detected by fresh gas and into the second Cyclone conveyed, while the gas from the second in the first cyclone together. flows in with fresh solid.

In order to keep heat as lossless as possible during exothermic processes in the cyclones To win, the cyclones are built with double walls or with pipes and with the outside surrounded by a heat insulating layer. Through the double jackets or pipes are Water vapor, water or other liquids, gases or vapors passed through, which are to be heated, or there are liquids in the double jackets or pipes evaporates. ' : -If you want endothermic processes to take place in the cyclones, so become hot through the double jacket or tube - liquids, gases or vapors that are to be cooled, or the cyclones are heated directly.

The inner surfaces are used to protect against heat and / or chemical attack the cyclones with heat-resistant, heat-accumulating and / or chemically resistant Linings provided.

Of course, the pipelines between the cyclones are also used analogously protected against heat and / or chemical attack and with double jackets or Pipes encased and thermally insulated.

Since in many reactions between solids and gases (e.g. ore reduction) the reaction rate from the diffusion rates in the solid particles depends, the reaction times are naturally the shorter, the smaller the solid particles are.

To increase the reaction time of reacting mixtures in the device extend without increasing the number of cyclones, the .Mix leading pipelines between the cyclones vortex chambers installed in a known manner, in which - depending on the clear width and length of these chambers - the reaction mixtures react for a certain time before they get into the next cyclone and there be separated.

The use of cyclone batteries according to the invention is better Understanding explained using the following example; Embodiment made of Fez03-containing Iron ore (Fe content 30%) is said to be FeC13 by reducing chlorination using coke (C content 75 ° / o} and chlorine can be obtained.

Ore and: coke are ground to grain sizes of 0 to 0.05 mm and reacted with chlorine at 800 ° C continuously and according to the countercurrent principle. The process is strongly exothermic, the heat released should be used to generate steam (approx. 34 at). According to the reaction equations 65 kg of coke and 720 m3 of chlorine are required per ton of ore at 800 ° C. After chlorination, 706 kg of gangue (including coke ash) remains, and it. 830 m3 of gaseous chlorination products are produced, consisting of ferric chloride and carbon dioxide. Therefore, only about 1 kg of dust is caused to react per cubic meter of gas, which is very unfavorable for rotary kilns or fluidized bed towers. Relationship.

In this case, cyclones are used to carry out the process, such as the one shown in FIG. 3 shown schematically: This consists of a magnesium spinel body a, a steam pipe casing b, a layer of slag wool c and a sheet metal cladding d. The steel of the steam pipes contains 20% Ni and 25% Cr.

The powdery ore-coke mixture is introduced into pipeline 6 (FIG. 2) in front of cyclone 1 , for example by a water-cooled screw conveyor, where it is captured by the gas flow coming from cyclone 2 and - mixed with it - is blown into cyclone 1. The gas from cyclone 2 contains a small amount of C12 in addition to a great deal of FeC13 and C02.

In cyclone 1 (FIG. 2) some of the Fe 2 O 3 contained in the ore reacts with the coke dust and the last amount of Cl 2, which is completely consumed and converted into FeCl 3. In cyclone 1 , the ore-coke mixture is separated from the gaseous mixture, which only consists of FeC13 and CO . The gas escapes through pipe 7, while the ore-coke mixture enters pipe 8 . Here it is captured by the gas flow coming from cyclone 3 through pipeline 9 and - mixed with it - blown into cyclone 2 through swirl chamber 14. The gas from cyclone 3 contains more Cl and less FeC13 than the gas from cyclone 2.

In Zyklon 2 , another part of the Fe203 contained in the ore reacts with the coke dust and the C12, producing FeC13. In Zyklon 2, the ore-coke mixture is separated from the gaseous mixture which, in addition to FeC13 and CO, also contains a remainder of chlorine. The gas escapes through pipe 6, while the ore-coke mixture enters pipe 10 . Here it is captured by the gas flow coming from cyclone 4 through pipeline 11 and - mixed with this - blown into cyclone 3. The gas from cyclone 4 contains more C12 and less FeC13 than the gas from cyclone 3.

These processes are repeated analogously in the rest of the cyclone series, until finally the fresh Cl supplied through pipe 12 reacts with the dust from cyclone 4 in cyclone 5, with the last Fez03 residues in the dust being converted to FeC13 and CO . The gas, which consists of a great deal of Cl and very little FeC13 and CO, passes from cyclone 5 through pipeline 13 (taking along the dust from cyclone 3) into cyclone 4, while the gangue leaves cyclone 5 as iron-free dust. Water is passed through the pipes surrounding the cyclones and the connecting lines, with a vapor pressure of about 34 at (corresponding to about 240 ° C.) being maintained.

C12 slowly diffuses through the pores of the magnesium spinel wall, so that the surface of the steam pipes is covered with a firmly adhering layer of CrC12, NiC12 and FeC12. Since the vapor tension of these chlorides is practically zero at temperatures of up to 500 ° C and the pipes in the cyclone jacket are in a standing atmosphere, they are no longer attacked.

On the one hand, the heat-retaining wall made of magnesium spinel prevents that the reacting substances are cooled below 800 ° C and, on the other hand, that the Steam pipes heat is supplied too quickly. The reaction temperature in the cyclones is regulated by controlling the rate of water flow in the steam pipes.

As a result of the countercurrent principle, the excellent heat transfer between swirling gases and dusty solids on the one hand and the very good heat transfer between these mixtures in the vortex state and the walls of the cyclones on the other hand - and the practically complete thermal closure of the cyclone batteries to the outside, both the material conversion and the thermal efficiency in the processes according to the invention according to patent 1136 722 surprisingly high.

Claims (1)

Claim: Process for the production of pure iron and / or iron oxide by halide metallurgy, whereby finely ground coke, finely ground iron-containing ore, dusty gangue and Fe203 dust are reacted in countercurrent with chlorine or a mixture of gaseous chlorides and nitrogen and reducing gases , according to patent 1136 722, characterized in that the heating and drying of ground coke, the heating and drying of ground ore, the reducing and oxidizing chlorination, the heating of nitrogen with the hot and powdery gangue and the reduction of iron oxide dust with reducing gases to iron in cyclone batteries of a known type. Documents considered: German Auslegeschrift No. 1085 502; German interpretation B 34008 IVa / 12g (published on July 26, 1956); German patent application St 3933 Ia / 241 (published on March 5, 1953); French Patent Nos. 879 652, 1108 186, 1108 623; USA. Pat. No. 1528 995th