DD254770A1 - PROCESS FOR RADICAL REDUCTION OF INORGANIC CHEMICAL COMPOUNDS - Google Patents

Abstract

The invention relates to a process for the radical reduction of inorganic chemical compounds such as oxides, sulfides and other reducible compounds to the elemental state or to a lower oxidation state. By intimate mixing of the material to be reduced with solid, liquid or viscous low- or low volatility hydrocarbons and subsequent heating to radical-forming cracking conditions short-lived, reactive, hydrocarbon radicals and hydrogen are formed in the status nascendi, which react directly with the metal compound. Much lower reaction temperatures are necessary and some process steps are saved.

Description

Field of application of the invention

The invention relates to a process for the radical reduction of inorganic chemical compounds such as oxides, sulfides and other reducible compounds to the elemental state or to a lower oxidation state. Preferably, this method can be used in metallurgy, for the production of metals from ores or other raw materials, in particular for the production of highly pure metals and / or defined metal compounds.

Characteristic of the known technical solutions

Numerous processes are known in the metallurgical industry, according to which the metals or defined metal compounds can be obtained by reducing the compounds present in the ore or other raw materials.

As a reducing agent carbon carriers, especially cokes of various qualities, are used, which were obtained by coking coal, lignite, bitumen or other hydrocarbons.

In addition, for many metals, the electric current must be used as a reducing agent if the metals are to be obtained in sufficient purity.

It is obtained, for example, by reduction in the blast furnace process from mixtures of iron ores and coke and using large amounts of energy pig iron, which is further processed in subsequent process stages in technically required steel and cast iron qualities.

The reduction process in the blast furnace can be described in a highly simplified representation by the following equations:

Fe ₂ O ₃ + 3CO - »2Fe + 3CO ₂

CO ₂ + C ^ 2CO

Fe ₂ O ₃ + 3C-> 2Fe + 3CO

To convert the present in the ore into easily fusible calcium and aluminum silicate slags flux are added. This increases the slag content and the specific energy consumption in the oven.

As a result of the bed height of ore and Möller in the blast furnace, these feedstocks must be given in a very stable form and to ensure the passage of the furnace and reducing gases in sufficient quantities. Therefore, much attention is paid to the preparation of suitable pellets, optionally enriched and pre-reduced ores. The entire process sequence requires relatively high technological and human resources.

The preparation of other metals from metal oxides or corresponding metal compounds with coke or carbon as the reducing agent proceeds under similar conditions and analogous reactions.

There are also known processes in which metal oxides are reduced by introducing CO gas or CO / H ₂ gas mixtures to metal. The running chemical reactions are similar to those that occur in the blast furnace process, but have the particular disadvantage that the relative consumption of reducing agent is higher than in the coke reduction, because already half the oxidation state of the carbon is reached. The total amount of gas applied is therefore considerable and the bulk material must be correspondingly loose, which in turn requires expenses for pelletizing the material to be used.

As a reducing agent for metal oxides and sulfur-containing iron ores and methane, acetylene, propane, butane and similar gaseous hydrocarbons are described. In this case, preference is given to working at temperatures above 1.273 K, but in some cases below the metal melting point.

In addition, this method can also be operated in an electric arc. In this case, the gaseous hydrocarbons, such as methane, ethyne or propane, are converted into CH _x radicals, with χ = 1 to 3, which reduce the metal oxide introduced with the deposition of elemental metal.

This process is similar to known arc and plasma processes and uses hydrocarbons for radical formation and reaction and is associated with high energy consumption because of the high temperatures required.

Liquid hydrocarbons are also used as reducing agents for certain metal ores. The oil is converted as a carbon carrier at very high temperatures and with the supply of air or oxygen-containing gases to carbon oxide and only then acts as a reducing agent.

In a further number of processes, organic compounds, in particular heavy oils, tars, pitches, but also polysaccharides, starches, fats, alcohols, waxes and other organic substances are described as binders and prereducing agents, in particular for the production of pellets from ores or other raw materials. The pellets thus obtained are coked in subsequent technological stages and reduced by the method described above, usually with the additional addition of reducing agent to the metal. The reaction temperature is preferably above the melting point of

recovered metal. ,

The main defects of the previously known methods are their multi-stage operation and in the application of high temperatures, which extend to the arc and plasma temperature.

The process sequence

- mixing of the metal carrier (ore or other raw material) with the carbon carrier (coke, coal, hydrocarbons),

- coking of the mixture,

- Hardness annealing,

Use in the reduction furnace, optionally in admixture with further reducing agents and reduction to the metal,

Melting and parting off of the liquid metal or removal of the metal from the coke matrix

is therefore very expensive in terms of personnel and material costs and also in terms of energy consumption.

Object of the invention

It is the object of the invention to develop a process for the reduction of metal-containing compounds, which reduces the disadvantages mentioned and can be carried out at lower temperatures and with fewer process steps.

Explanation of the essence of the invention

The invention has for its object to reduce metal compounds or ores using organic chemical compounds and directly to the elemental state or in a lower oxidation state.

According to the invention the object is achieved in that the inorganic compounds to be reduced are intimately mixed with liquid, viscous or solid bitumen, tar products, pitches, olefins or other easily or non-volatile chain or annular hydrocarbons and heated this mixture to the specific reaction temperature

The reaction works best when it is possible to bring the substances reacting with each other in the most intimate contact.

This is conveniently done by mixing coarse to very finely ground inorganic materials with liquid to viscous carbon carriers at temperatures below 373 K or by dropping the reducing agent on the crushed ore or other appropriately prepared raw material, which or previously heated to the specific reaction temperature has been.

It has surprisingly been found that the reduction of the inorganic chemical compounds to the element or in a lower oxidation state proceeds at far lower temperatures than the previously known methods.

In this case, the hydrocarbon radicals which form during the thermal cracking of hydrocarbons and have a short-lived, reactive hydrocarbon radicals and the present hydrogen act in the status nascendi on the metal compound.

The course of the reaction is very complicated and in detail not yet elucidated. In a simplified form, it can be approximately described with the following equations:

(1) R-CH ₃ ^ R-CH ₂ + H-

(2) MeO + 2H- ^ Me + H ₂ O

CH - R

(3) HeO + 2R - CH *> MeO ' ²

^V CH ₂ - R

(4) MeO '

, ^CH 2 - ^R

, 2>

(5) 2 MeO -v 2 Me + CO ^ ₊ H _{0 +} R -CH ^ -R

¹ CH ₂ - R 2 2 lbs

These described reactions are underpinned above all by the detection of H ₂ , H ₂ O, ethers and CO ₂ in the reaction products.

The use of highly purified inorganic compounds and reducing agents, while using a suitable vessel material, produces high purity metals or lower valency metal compounds for specific applications.

The reduction process can be operated so that the addition of hydrocarbons takes place in a well-defined amount and remain in the reaction oven after completion of the reaction, only the metal and the corresponding slag residues, which are separated by known methods.

The resulting fission gases are preferably fed to an energetic use.

If you work with an excess of reducing agent, usually arise products that consist of a coke matrix and embedded metal. By dissecting out the metal, e.g. B. by melting or by chemical reactions, coke can be obtained in addition to the metal, which can be used in the case of the use of sufficient pure substances for special purposes.

embodiments

Reference to the following embodiments, the inventive method according to the reduction of tin compounds will be explained in more detail.

example 1

200 g of SnO ₂ is mixed with 100 g of lignite coal tar and this mixture is slowly heated to 1173 K in a normal coker or in a coke blast. After completion of the reaction, tin is obtained with a yield of 98.8% and coke in a yield of 39.9%.

Example 2

According to Example 1, the mixture of SnO ₂ and lignite coal pitch is continuously fed to a coke blast and the reduced and molten tin is withdrawn at the bottom of the bladder.

The process is interrupted when the vessel has been filled with coke. After cooling, the coke is discharged and the system is ready for use again.

In addition to tin, a coke suitable for the production of electrodes is obtained in good yield.

The resulting in this process liquid products can be used in a known manner for fuel production and the fission gases for energy purposes.

Example 3

200g of high purity SnO _{2 was} mixed with 100g of chemically pure decalin and the mixture was reacted in a stainless steel bladder. Upon reaching a temperature of 1173 K, the reaction is completed. The melted high purity tin is obtained with a yield of 95.7%.

Example 4

200 g of SnO ₂ are heated to 873 K in a reaction vessel, and then preheated pyrolysis oil is slowly added dropwise. This results in the reduction to metallic tin. The reaction is completed when coke formation occurs in the reactor.

Claims (6)

Invention claim: 1. A process for the radical reduction of inorganic chemical compounds to the elemental state or in a lower oxidation state, in particular for the production of metals and / or defined metal compounds, characterized in that the material to be reduced at normal or elevated temperatures with solid, liquid or viscous bitumen , Tar products, pitches, olefins, or other low or low volatility chain or ring hydrocarbons, and that this mixture is heated to radical-forming cracking conditions. 2. The method according to item!, Characterized in that the inorganic chemical compound is heated to the specific radical-forming cracking conditions and that the reducing agent is optionally dropped in the preheated state. 3. The method according to item 1 and 2, characterized in that it is preferably carried out in a temperature range of 573 to 1173 K. 4. The method according to item 1 to 3, characterized in that it is used to produce reduced inorganic substances and special coke with a reducing agent excess. 5. The method according to item 1 to 3, characterized in that the reduction is carried out in a hydrogen atmosphere. 6. The method according to item 1 to 3, characterized in that highly purified starting materials are used for the production of highly pure metals or metal compounds.