DE2156323A1 - METHOD AND APPARATUS FOR REMOVING OXYGEN FROM OXIDES - Google Patents

Description

Patent attorneys

Dlpf.-Ing. A. Gröneckef _p

Dr.-Ing. H. Kinkeldey t

Dr.-lng. W. Stockmalr Dr. rer. kind. W. Fischer
Munich 22, Maximilianttr. 43

SERVICIOS DE INGEIiIERIA PROTECTOS Y ESTUDIOS (SIPEC), Loiidres 63 »Barcelona 15» Spain.

Method and apparatus for removing oxygen from oxides

The invention relates to a method for removing Oxygen from oxides, after which the feed consists of mineral to be deoxidized and solid reducing agent, the is conventionally located inside the chamber, by indirect heating through the chamber walls, without Contact at any time between the loading and the means or heating gases used as heating means, Should these be present, depending on the fuel used for heating or the energy source, is treated, as well as a device for performing the method.

Iron is the most common metal used by humans. It is extracted from its ores, which are in the majority of the

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of the cases found in nature in the form of oxides. At this point they have to be reduced .; that is, their oxygen must be grounded away.

From the metal age to the present day, innumerable methods and devices have been proposed for reducing iron ore, with the furnace being the most important of all.

Notwithstanding the fact that almost all of the iron ore is in the

jstetsv Blast furnace is reduced, was / aimed to abandon this process, since facilities of this kind larger investments (which are prohibited in certain countries) and because metallurgical coke (which is very rare all over the world) is required for ore reduction.

Among the methods and devices that have been proposed to replace the blast furnace are those that have been used as cryogenic reducers (lower than for softening and melting iron) are known to be a solid product provide what is commonly known as a sponge iron as in the present case.

From this point of view, it can be pointed out that that over a hundred years ago processes and devices for reducing iron ore at low temperatures were patented became. A solid reducing agent (coal) was used which, mixed with the ore, was placed in vertical reduction chambers was introduced.

The chambers were extremely heated on the outside, the load contained in them (mineral and reducing agent) received the heat indirectly.

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Once the reduction of the mineral (a rather incomplete reduction) was "finished, the feed was cooled, before they are removed from your oven.

Not only have methods and devices been proposed and patented, but various plants have been built in several countries, including Spain

Among the various processes and equipment that are in front of many Years proposed were those by Chenot, Blair, and Yates matter. Chenot's work, including the Patents started around 1855. Blair and Yates started somewhat later. The devices used by all of them consisted of furnaces with one or more vertical reduction chimneys, where the transvex ^ -sal-horisr.ontal cross-section of the same circular, rectangular, etc. «. was «, the chambers were out refractory material, i.e. from a poor heat conductor, educated.

The methods and devices mentioned did not provide any good results, since they could not compete with the blast furnace, since, as already stated, the ore reduction is quite good was incomplete. Furthermore, as a result of indirect heating, they required high energy consumption (due to the poor Heat conductors as chamber walls).

No doubt Chenot and others wanted to avoid the latter and changed the heating process by feeding some of the heating gases through the charging system. «Da the hoped-for results did not occur, their facilities closed one by one.

The same has been related to the case in much more recent times with numbers that are similarly based on the Chenot principle

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indirect heating of the feed was based «. However, materials that conduct heat well (silicon carbide, hit-resistant steel and specializations, etc.) were used in the construction of vertical chambers. and the energy required for heating remained excessive. Equally inadequate to compete with those based on blast furnaces, these facilities suffered the same fate as those of Chenot, Blair, and Tates. So far, the existence of a plant of this type is unknown anywhere in the world . *

In view of the current great interest in many countries in low-temperature reduction processes, the processes and equipment used by Chenot, Blair _% Yates and Ariderenj for vertical reduction chambers with indirect heating of the feed contained in them have been exhaustively investigated . The purpose of these investigations was not only to ascertain the reasons why the results of these processes and systems were modest, but also to determine precisely and with certainty whether these processes and systems could, because of these causes, be improved so that they could be used with reduction systems could compete on the basis of modern blast furnaces.

The results of these investigations were clearly satisfactory, there is no doubt that, by application of the improvements in method and apparatus referred to later is a product is achieved, which is very competitive with that of the blast furnace and at the same time some of the major problems that presently in the metallurgical field, solves. These are:

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In many developing countries (which are often rich in minerals are.) the creation of integral metallurgical plants on the basis of a "reduction" to enable at a low temperature;

the capacity of these plants to fill the national needs · Iron and steel products as well as to the economic ones Possibilities to adapt (systems based on modern Blast furnaces require high investments, which many countries are unable to finance, and their high production cannot always be taken up by the country) j t

Low temperature reduction plants are profitable. the production being much less than that considered for a modern, profitable blast furnace. Minimum. The pro installed ton / year required investments are likewise much lower)

the industrialization of these countries would thus be encouraged, and by doing so their needs for iron and steel products were resolved $ they were stopping exporting countries only for Minerals and other raw materials;

finally also to bring about the reduction of iron ores, without having to resort to Ilüttenkohle, which is inevitable in blast furnaces and a real problem all over the world due to the scarcity of coal Represents coking.

This would not only come from developing countries (which often Coal for coking and coke are missing), but also the more industrialized countries. An example in this direction is the fact that the United States, regardless of its exports of coal for coking or coke in

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half the world, start making plants to reduce at lower to build up temperature.

The study referred to earlier showed without any doubt that reactions between the reducing agent and the mineral occur in indirectly heated verticals Reduction chambers operated under very modest conditions. The third was: "The reactions started slowly in coldest part of the chamber (upper part of the same) continues at low speed in the time in which the Loading entered through the middle of the chamber, then accepted Intensity from until they were almost zero or zero when walking through the heated (lower) zone of the chamber. "

From what has been said before, the following results: The reduction chamber was only partially (in its upper and Gown part) where, since the temperatures were not high, the reactions could not be effective.

The responses began to wear off in intensity when some, rather incomplete, degree of ore reduction was reached, which took place in the lower middle of the chamber.

Due to the lack of reducing gas, the reductions were in the lower part of the chamber, which was generally best heated, already minimal.

Practical results from this were as follows: A product - sponge iron - was obtained with generally not a high reduction, since the reaction was interrupted precisely when a certain * degree of reduction was achieved

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Increasing production per chamber as a result of the fact that not mohr were used as the upper and middle part where the Responses not effective

High consumption to heat the load * During this is always the case with every indirect heating system emphasizes this particularly in the cases under consideration, aufganmd the fact that the most heated part coincides with a zone in which practically no reactions took place.

An expensive product of average quality was obtained which the product of blast furnaces did not could compete "

Careful studies of the problem and a variety of experiments have now been carried out, leading to a conclusion led to the fact that the earlier failures can be completely resolved by:

1. The heating chamber is fully utilized; itself a part the cooling chamber can be used for reduction purposes.

2. The reduction takes place effectively at all times without interruption, with high reduction being achieved which

. is worth seeing for a quality product and so far could not be reached.

3. The effective and uninterrupted reduction reactions take place in a heated chamber, with this chamber being fully utilized, a high productivity per chamber is achieved, combined with a corresponding reduction in heating costs.

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A-, The chambers can not only be used for the pure reduction of iron ore in the manner indicated, but obtained, reduced iron can be treated by more or less carburizing it, as desired, and lowering its sulfur content »This is extremely important because it would provide a furnace for the reduction and treatment of iron ores instead of a mere reduction furnace for the said minerals.

These four results are obtained by using gases other than those for heating. They are strong reducing agents that are introduced into the chamber at various levels, the highest level being at a level lower than that of the lowest heating part or the heated chamber.

Implementation of the foregoing represents the improvements in the. Methods and devices are used for removing Oxygen present in oxides are used and thus represent the invention.

The inventive method for removing oxygen ^ from oxides, after which the charge of to be deoxidized "** 'Mineral and solid reducing agents that are found in conventional Sometimes located inside the chamber, by indirect heating through the chamber walls, without contact at any time depending on the charge and the means or heating gases used as heating means, these should be present of the fuel used for heating or the energy source, is that in different Heights below the chamber zone, which is conventionally referred to as the heating zone, preheated, strongly reducing gases such as

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CO and Hp, individually or together, to form a through the feed ascending, catalytically active, the reductions accelerating, deoxidizing and treating streams occurring in the feed to improve the properties of the obtained carburized and desulfurized metal product.

The invention is further directed to a. Device with one or more vertical chambers (η), located mainly inside the furnace, through which a heat source passes, which transfers the heat indirectly to the load inside the chamber and in the heating zone, with one from the upper part of the The protruding part of the furnace, which is intended for loading, is called the preheating zone, with a cooling zone at its lower part, which is connected to devices for drawing off the product, and another zone, known as the holding zone, between the cooling and heating zones, in which the temperature of the Feeding is maintained when the latter sinks under its own "weight to the lower zones, which is characterized by the fact that the chamber in the warming zone and in the cooling zone is equipped with a number of supply lines, which at different heights complementary to others, d to Drain certain, which are located near the top of the heating zone, with the one below the He izzone-lying lines with devices for blowing a gas or a mixture of preheated gases into the interior of the chamber, the lines in the upper part of the heating zone * with devices for drawing off the one or those blown in from below as well as those formed during the reactions taking place in the chamber Gas (s) are connected.

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Other Features, Details, and Advantages of the Invention emerge from the following description, which does not restrict the invention, of exemplary embodiments with reference to FIG Drawing.

Figs. Λ and 2 show the section τοη the side or * in a plan view of a Besoxydations- and. Treatment device in only one chamber, a device which is heated in its ninteiei area and in which the heating gas © rises. Figures and 4 show a section from the side and in plan view Jg; a system equipped with two double chambers, which are arranged in a set, a system that is heated from its upper part and xb which circulates the heating gases downwards.

To avoid repetitive descriptions and that Understand the figures corresponding to each of the plants enable, the corresponding parts thereof have been given the same reference numerals

■ -A-shows the chamber in its.first, preheating part where at -1- the charge enters the chamber; -2- called the walls of the same with refractory, insulating Material and -3- air let in to the Vötr heating chamber, which open • are evenly distributed around the circumference of the chamber. -B- shows the second, heating part of the chamber, with chamber gases at -4- erx-calibrate the upper part of the heating zone and from there through a number of openings arranged for this purpose on the larger side walls escape; -4 '- are lines, by which the aforementioned gases are sucked out of the furnace where water (through condensate! © ») and COp (absorption) are removed, whereby the residual gas (mainly formed from CO and Hp ") can be reused; -5- are div

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Chamber walls which in the heating zone consist of silicon carbide or a material with analogous properties ", the chamber having a practically right-angled section, the smaller walls of which are vertical and the larger walls of which are vertical or slightly inclined in order to allow the load to drop through the interior to facilitate, and ~ 6- are gases in the chamber rising through the interior of their heating zone. -C- shows the third chamber zone, the holding zone, with inlet - '/ - for strongly reducing gas to the holding zone through a number of nozzles, which are for this purpose: on their walls, which can consist of silicon carbide or any other suitable refractory material, with supply lines -? '- for strongly reducing gases for this chamber area. -D- is the fourth, the cooling zone of the chamber with inlet openings -8- and -9- for strongly reducing gas to this cooling zone through a number of nozzles, which for this purpose are on their jacket walls made of double iron sheet with pressurized water cooling in between; -8 ¹ - and -9 '~ are lines for the entry of strongly reducing gases * for this part of the chamber; -10- are the walls or the jacket of the chamber in this cooling zone, the height of which is sufficient to allow the deoxidized iron and other components of the charge to arrive completely cooled at the lower end; -18- are inlet and outlet openings for the cooling water from this chamber section; -11- shows the unloading mechanism of the plant, which can be of any of the types used for this purpose in industry (e.g. rotary drum) and in the same continuous manner delivers the deoxidized and cooled charge, v / whether an unloading mechanism is provided for each chamber is; -12- shows the locking system for the lower part of the chamber. _t It consists of two

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Shut-off devices which cannot be opened at the same time and, if operated one after the other, allow continuous draining of the charge without substantial amounts of tuft entering the chamber: - 13- shows deoxidized and cooled ore which, together with superfluous binding agent, is brought in and not was used, -and is drained from the system with the ash of the used reducing agent; -14- shows Eintrittsoffnringen in the heating device used, where 1 is the system in the Fig. And. from the lower part, which is heated in FIGS. 5 nod 4- from the upper part; -15- shows Kauiaerheizgase, which rise in Figs. 1 and 2 and in Fig _e 5 ^ next ^ - after. im.ten lead; -16- shows outlet opening of the plant for Sase for heating the chamber, and -17- shows the lining of the plant made of a refractory and insulating material.

The chambers are loaded at regular intervals and, of course, from their upper (preheating) area, with the drying and vigorous preheating of the loading taking place one after the other in this zone. Piping two effects are obtained by heat generated in the Terbrerrotmg of gases dterchi the Vorheizbereicli the rising fe reach through the chamber interior, and a small amount of reducing agent which is introduced in excess, the Era together with an amount of air accompanied _s is introduced through openings, which for this purpose are arranged in a lower part of the preheating area. Since the atmosphere in this first area of the Earner is oxidizing, no deoxidation of the ore will take place here. Deoxidation is initiated at the moment when the heavily prearranged charge enters the second, the heating zone of the chamber, the atmosphere of which is strongly reducing.

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The feed is made by the deoxidizing to be treated and to ■ ore and the solid reducing agent used *: the latter may be added to a suitable desulfurizing _agent} to prevent the sulfur in the reducing agent contaminates the ore.

The mineral is crushed and conquered, or brought in agglomerated (briquetted, sintered, in the form of pellets, etc.). Shall iron ore minerals be deoxidized and. Any natural or man-made oxide (hematite \ magnetite, calcined carbonate, roasted pyrite ash, etc.) can be used. While crude (uncalcined) iron carbonates could be introduced, it is economically desirable to calcine them prior to introduction into the deoxidizing and treating plant.

Likewise, the reducing agent is sieved, for which each species known solid reducing agent can be used (Anthracite, metallurgical coke, non-metallurgical coke, low-temperature coke, partially distilled coal, gasified lignite, charcoal etc.). Should the reducing agent contain an amount of sulfur that could contaminate the mineral, can desulfurize any suitable amount Means (limestone, lime :, dolomite, etc.). added to prevent this.

The charge ultimately consists of an intimate mixture of mineral and reducing agent (always in excess is added to the required amount) and the desulfurizing agent (should this prove to be necessary).

In the event that the mineral is an agglomerate (briquetted, sintered, as pellets etc.), the latter can

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all or part of the reducing agent and the necessary desulphurizing agent are added * - "" - . ' ^r s:.: Li.

The deoxidation of the mineral becomes "ί <-νί-." in which the loading 'in the first chamber area icil'. strongly preheated, penetrates into the second or heating part, vfo it encounters a strongly reducing atmosphere o

So the deoxidizing process begins with a mixed one Reducing agent, since deoxidation takes place with two completely different reducing agents: the solid reducing agent, which, since it was mixed with the mineral before it was placed in the furnace, this during the entire route accompanied through the four chamber zones? and the gaseous Reducing agent, which, as it is in the cooling and warming » zone of the chamber is blown in with the mineral, whereby it is in the cooling zone in the upper half the same and vice versa in the warm and heating zone the chamber circulates, =

The chamber walls in this second heating part are made of silicon carbide, a material that is not only resistant to high temperatures resists without being deformed or changing, but is further known for its high thermal conductivity is what is fundamental for an indirect heating system, where the feed is heated by heat transfer takes place through the walls without there being a connection through which the charge is within could bring the heating media into contact, which circulate outside the chamber.

Instead of silicon carbide, a metal, an alloy, etc. can be used, these materials having properties

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similar to those of silicon carbide. At present, substitute materials equal to or better than silicon carbide sinaj are not available in normal industry. It is anticipated, however, that materials will be developed and used in the air and craft industries ₅ which at some point will become available for other uses.

It should be remembered that the narrower walls of this second chamber part are vertical, with their transversal

horizontal section is practically right-angled, while *

its wider walls can be slightly inclined to f

to facilitate the lowering of the load through its interior *

The system is heated between the heights corresponding to this second, heating zone of the chamber. Any fuel or any combination of fuels, whether solid, liquid, gaseous or other heating (combustion gases, hot air, electrical energy, etc.) can be used.

Hot gases flow through the chamber wall between the specified heights along with a usually vertical movement (ascending or descending * depending on the way in which the gases of the system flow out, from the bottom or from J above). But you can also go around differently.

The third (a) part of the chamber, the warming part (e) holds the load inside for a certain time at a high temperature, so that, since the deoxidation process takes place here at a rapid pace, the load takes the fourth and last, namely the Cooling part of chamber (d) strongly deoxydiex ⁱ t reached.

To achieve the latter, to continue the oxidation process quickly, gets a certain amount of reducing gas into the

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Charge is blown in, with it to the inside of the holding chamber flows through a number of openings arranged on its walls for this purpose * So becomes this chamber section, instead of lacking reducing gas, which is the case in 'systems equipped with vertical, indirectly heated chambers', and in which the Deoxidation is achieved with solid reducing agents, using highly effective reducing gas at a suitable temperature filled, and for this reason, and especially thanks to the injected reducing gas, the deoxidation process is running quickly.continue.

By blowing in strongly reducing gas at a suitable temperature the reactions are in the warming zone of the chamber in the warming zone and in the lower heating zone too noticeably activated by a small amount of gas.

This is in fact done by injecting more reducing gases, always at a suitable temperature, into the fourth and last Zone, the cooling zone of the chamber, on two or more levels through those placed on the walls for this purpose openings increased and improved.

To do this blowing at the specified levels, the following reducing gases are used: CO (carbon oxide) and Hp (hydrogen), either together or separately.

If these gases are used, the deoxidation of the ore is not only improved and the production per chamber increased, but the metal obtained is treated. For the purpose of deoxidizing the mineral, it should be noted that CO is ^{particularly effective at temperatures between 900 and 1050 0} C, while

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V / on Hydrogen 500 "to 600 ⁰ C and requires 1000-1100 ⁰ C. It should also be recalled that the reduction of iron oxides with CO is slightly exothermic, while the reduction thereof is slightly endothermic with Hp. Showing At 900 ⁰ C, the Reduction of iron oxides with a mixture of CO and Hp with approx. 4-8 % Hp no heat release. CO and H ^ gases rising through the interior of the chamber contribute to improving the ore deoxidation, since the flow of the gases and their deoxidation capacity increase «,

For the purpose of treating the reduced iron ore, it should be noted that Hp serves to lower its sulfur content, while iron with carbon (C) of 0.2% (this would be the Pail with representative carbon when the deoxidation is carried out only with a solid reducing agent) up to 1 % (when using a gaseous CO reducing agent plus a solid reducing agent).

The fact that the sulfur content decreases and increases and the carbon content can be varied are how well known in ferrous metallurgy, two points of high Meaning.

The gases rising through the interior of the chamber consist mainly of CO and CO ₂ (created in the reactions between the ore and the solid reducing agent introduced), CO and Ho (blown in) plus CO ^ and HpO (created in the reactions between the ore and the reducing gases blown in. Even small amounts of nitrogen (Np) are due to small amounts.

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Air entering the chamber through the double A "b lock syst em in may have penetrated their lower area.

These gases are sucked out of the system, whereby CO-Hp is recovered and the CO ₂ (by absorption) and the HpO (by condensation) are removed.

The recovered CO and Hp are either in the same System (as a reducing agent or for heating the chambers) or decayed elsewhere (for any other purpose).

The deoxidized and cooled mineral is used together with the solid, in excess and unused reduction agent from the system through the discharge mechanism, which is located in the lower part, applied. A locking system with two barrier organs, - which are in the lower part of each Chamber is located, and its shut-off devices not at the same time can be opened, allows the chamber to be emptied or unloaded without any significant amount of air in it Can penetrate the interior.

- Pa t demands -

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Claims (2)

Patent claims 1. Process for removing oxygen from oxides, after which the charge of mineral to be deoxidized and solid Reducing agent, which is conventionally located inside the chamber, by indirect heating by the Chamber walls, with no contact at any time between the charge and the means used as heating means or heating gases, should these be present, depending on the fuel used for heating or the energy source, is treated, thereby, marked e i c hn e t " that at different heights below the chamber zone, which is conventionally referred to as Heizsone., preheated, strongly reducing gases such as CO and Hp individually or together forming a catalytically active one that rises through the feed, those taking place in the feed Accelerating, deoxidizing reactions and injecting the feed of treating stream to improve the properties of the obtained carburized and desulfurized metal product. 2. Apparatus for performing the method according to claim 1, with one or more vertical Eammer (s), predominantly placed inside the ovens through which a heat source runs that indirectly transfers the heat to the feed within the chamber and in the heating zone, with a the part that protrudes from the upper part of the furnace and is intended for loading, called the preheating zone, with a cooling zone aii its lower part, which with 309813/0685 -so- 21S6323 Means for removing the product is connected, and a further, known as the warming zone between the cooling and heating zone, in which the temperature of the load is maintained when the latter falls under its own weight to the lower zones, characterized in that the chamber in the warming zone (C) and in the cooling zone (D) is equipped with a number of supply lines (7 ^f t> between 8 ¹ , 9 '), which are at different heights complementary to other (16) _v which are located near the upper end 'of the heating zone (B), the lines below the heating zone with means for injecting a gas or a mixture of preheated gases into the interior of the chamber, the lines in the upper part of the heating zone with means for extracting the or the gases blown in from below and also the gases (s) formed during the reactions taking place in the chamber. 309813/0685 e r e i t e