US1864655A - Process for the production of ore coke - Google Patents

Description

Patented June 28, 1932 UNITED STATES PATENT OFFICE HANS KLENCKE, OF FRANKFORT-ON-THE-MAIN, GERKANY, ASSIGNOR '10 AMERICAN LURGI CORPORATION OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK PROCESS FOR THE PRODUCTION OF ORE COKE No'Drawing'. Application filed March 19, 1931, Serial No. 528,942, and in Germany April 2, 1930.

This invention; relates to a process for the production of ore coke.

In order tobring finely divided ore into a suitable form for further treatment, it has already been proposed. to mix the ore with coking coal and to gasify the mixture so as to produce ore coke. These known processes were always based on the principle of the known method of manufacturing coke in cokm ing chambers, and were accordingly always carried out in retorts, the coking being effected-as in coke-oven practiceby heating the retorts or chambers from the outside, or by passing hot gases through the charge in the n coking chamber. These known processes for the production of ore coke, whether intermittent or continuous, failed to make headway, in the metallurgical industry, which, being conducted on the large scale, requires large through-puts which could not be attained by the methods hitherto proposed. 7

The process of the present invention consists in coking the mixture of ore and coal in a sintering apparatus, either with a travelling grate on the principle of the Dwight-Lloyd apparatus, or also in stationary pans with the assistance of blowing. Operating with a travelling grate, after the manner of the Dwight-Lloyd apparatus, enables the operauous manner, whilst operating in the stationary pan provides, in known manner an approximately continuous process, with an output of ore coke sufiicient for large-scale industrial requirements.

In the process of the present invention, the ore is intimately mixed with a cokable ma- 4 terial, such as flame-coal or the like, damped and placed on the travelling or fixed grate of a sintering apparatus. The charge is then superficially ignited, and subjected to a top or bottom blast until coked. The blowing must, naturally, beperformed with air that is low in oxygen, and for this purpose the hot waste gases from the coking process itself, or I approximately inert hot gas from some other apparatus, may be suitably employed. Alternatively, air may be used, in which case a layer of material which lowers the oxygen a content of the blast air during its passage tionto be performed in a thoroughly continmust be disposed above or below the charge. For this purpose a layer of coal, for example may be employed.

In the process of the present invention, the coking process is conducted in such a manner that, after the ignition of the charge, the amount of atmospheric oxygen drawn or forcedthrough the charge-in the almost inert gas or air employed, in which latter case, a layer of coal or the like interposed in front of the layer of ore in order to obtain the desired result--is only so much as is needed for combustion for the generation of heat. The heat generated in those portions of the charge which are first exposed to'ignition, begins to distill thecoal situated there, and the distillation products burn in the atmospheric oxygen present. The resulting heat then cokes the adjacent layer of the mixture, and so on, until the coking process has gradually spread through the entire layer situated on the grate,

either from above downwards or vice versa. An essential point in carrying out the coking process is to ascertain the moment at which distillation ceases and the combustion of the resulting coke begins, since otherwise the risk is incurred that the reduction of the zinc. already occurs in the blast apparatus, and losses of zinc ensue. According to the present invention, the incipient combustion of the coke can be checked or prevented, in a simple manner, by sprinkling the coked charge on the grate with water, for example with the aid of a movable sprinkler.

The amount of cokable material in the charge must be so calculated that, after coking, the amount of the resulting reduction coke in the material corresponds to the reduc tion material in an ordinary muffle charge, consisting,'in known manner, of about 40 parts of reduction material per 100 parts of roasted blende.

The resent process is particularly suitable for coklng finely divided zinc material, in order to bring it into a particularly suitable condition for reduction in the mufile especially the vertical muflle. It may, naturally however, be applied to. coking other ores and materials.

When placed on the grate in a suitably moistened condition, the fine mixture of roasted blende and coal forms, at first, a compact layer, which does not assume a coherent porous form until later, as the result of the evaporation of the water and the gasification directly established, through the liberation of the water or the distillation products, when the charge is gradually exposed to the heat of ignition, and is brought about, in a particularly favourable manner, 7 especially when the process is performed ona travelling grate such as a Dwight-Lloyd apparatus,-owing to the slow rate of entry of the grate into the ignition zone. Since the distillation proceeds endothermally, there is no need to calculate on any great excess of heat resulting from the combustion of the hydrocarbons. In any event, by suitably regulating the amount of oxygen in the blast air, and suitably selecting the coking coal, the liberation of heat can be controlled in such a manner that almost complete distillation of the coal can be attained without the occurence of undesirable reduction of the zinc oxide through excessive disengagement of heat. Moreover, by suitably selecting the dimensions of the apparatus, the process can be performed in such a gentle manner that the mixture of ore and coal smoulders, as it were, and therefore the resulting temperatures do not exceed GOO-800 C., under which conditions no losses of zinc are to be expected. Furthermore, it is entirely unnecessary that the hydrocarbons should be completely removed, for if some of them should be left they will help to serve as reducing agents in the mufile. For this reason, it is advisable to operate with a slight excess of coking coal.

The advantage of the process of the present invention consists in that the resulting coke forms, in conjunction with the ore, a perfectly homogeneous coherent distillation material which (in contrast to the-hitherto customary muflle charges of fine material) results in a particularly favourable reducing action. In the ordinary mufiie charges, the desulphurized blende and reduction material form a loose mixture, in which the coke has to serve as a loosening agent as well as a re ducing agent, and therefore must not be in such a state of fineness as is needed in the interest of intimate contact between the reduchave to act as a loosening agent, but, in such case, the particles'of coke and material are in very loose contact and of comparatively large grain size, so that, in this case, also, the contact cannot be regarded as sufliciently intimate. These defects in the muflie charge are obviated in the material prepared by the process of the present invention. In this case, the particles of the reducing agent and of the material to be reduced are in particularly intimate contact, and, since the material is firmly coherent, cannot become segregated.

I claim 1. 'A process for the production of ore coke which comprises superficially igniting a mixture of finely divided ore and coking coal on a support that is permeable to gases, and subjecting the ignited mixture to a blast until the mass is coked without any substantial consumption of the coke or melting of the ore.

2. A process for the production of ore coke which comprises superficially igniting a. mixture of finely divided ore and coking coal on a support that. is permeable to gases, and blowing the ignited mixture with hot gases until the mass is coked without any substantial consumption of the coke or melting of I the mixture and subjecting the ignited mixture to a blast until the mass is coked,

5. A process for the production of ore coke which comprises distributing a mixture of finely divided ore and coking coal upon a support permeable to gases, covering the charge with a layer of coal, igniting the mixture and subjecting the ignited mixture to a blast until the mass is coked.

6. A process for the production of ore coke which comprises superficially igniting a mixture of finel divided ore and coking coal on a support that is permeable to gases, subjecting the ignited mixture to a blast until the mass is coked, and sprinkling water over the mass when the coal is substantially completely coked.

In testimony whereof, I aflix my signature.

' HANS KLENCKE.