US1733500A - Zinc-reduction apparatus and process - Google Patents

Description

Original Filed Aug., 31, 1921 r CL i y (V 'UCL 29, 1929. H, KOPPERS ZINC REDUCTION APPARATUS vAND PRCCEssJ Original Filed Aug'. 5l, i921 5V Sheets-Sheet Oct. 29, 1929.

H. KOPPERS ZINC REIIDUCTONAPPARATUS AND PROCESS 3 sheets-sheet 5 oiginal Filed Aug. 31. 1921 'Dm nl: um

Patented Oct. 29, 1929 UNITED STATES PATENT OFFICE A HEINRICH KOPPERS, OF ESSEN-RUI-IR, GERMANY, ASSIGNOR- TO THE KOPPERS DE- VELOPMENT CORPORATION, OF PITTSBURGH, PENN SYLVANIA, Av CORPORATION OF PENNSYLVANIA ZIN C-REDUCTION l APPARATUS AND PROCESS Application filed August 31, 1921, Serial No. 497,360, and in Germany January 8, 1917. Renewed october 19, 1927.

`10 these vessels; an oven of the customary construction in this connection holds from about 150 to 300 muiiles. In heating thecharge contained in the muiiles, the oxidizing gases and vapors escape first, on which account this stage of the treatment takes place at a low temperature, so that zinc may not be reduced at'A once and taken away or oxidized with the diluting gases and vapors, thus getting lost. When the oxidizing gases and vapors have been expelled, the temperature of the oven is gradually raised to white heat. Now, it is a well-known diiliculty to expel, 'in reduced form, the last particles of zinc which are still contained in the charge, and, as a general rule, this can only beA accomplished with permanent white heat in the oven.

The building material hitherto used for these muttles, which is clay-bound and fireproof, cannot stand these high temperatures very well, and there also form heavy scorifications between the residue of the distillation and the fire-proof building material. The idea of using line-bound, tire-proof building material, so-called Dinas stones, which are distinguished by their fire-proof qualities and greater resistance to alkaline action, is opposed by the disturbing phenomeof the ovens the lime-bound building material is subject to premature deterioration.

The invention solve's the problem of rendering a satisfactory use of lime-bound lireproof bricks possible for zinc muiiies operated stepwise, and rests, in this connection, on the realization that this is possible when due care i is-taken to 4heat the distilling chamber quite uniformly on the onev hand and constantly so high on the other hand that the heat withdrawal during the discharging andcharging can only entail a very slight detrimental lowering of the temperature. Such a uniform and' intense heating is allowable, however, if n the zinc mulles are made as chambers lafter the fashion of the coke ovens, which are always enclosed between two heating walls di vided into individual heatin iues and provided with burners that can ieregulated individually, and which are heated on the so l1 called' regenerating principlethat is with heat recovery in the high-grade regenerators. v

The bond of the heating walls among themselves, which is created by the headers forming the individual heating fines, also makes it possible in thisconnection to safely hold in the best manner the inner pressures occurring in connection with the distillation ofthe charge.

So as to also be able to regulate the heat'- ing ofthe individual chambers according to the viewpoints mentioned, regenerators are suitably divided as in coke ovens, into regenerators forming a unit with the individual.

ovens, without-the structural assembly of the chambers into an oven block being lost. The proposition of using large dimension ovens in place of the Zinc muiiles, has already been made, without the employment of the advantageous Dinas material on the one hand or constant and uniform heating on the other hand, or the characterized inner connection being utilized.

, The lime-bound lireprooil bricks already have the advantage that they resist basic action or influences, and thus scorilication, better, and this advantage can be still -further utilized by keeping the charge, by means of an insulating layer made of unmixed carbon, away from directcontact with the wall. yIn the reduction of metals, so as to make it possible conveniently to remove the molten metal cake from the crucibles, the proposition has also been made of lining this reducing vessel with an insulating layer. In the present case, however, other cond1t1ons enter into consideration, and, furthermore, the manner in which this insulating layer is made in each case, according to the operation of the zinc distillation, plays an `important part.

zinc ore to be reduced and the carbon necessa'ry therefore, the so-called cinder briquettes are made, for instance in the form of the well known egg briq'uettes, and these briquettes are supplied, at any one time, together with lo the proper quantity ofloose unmixed cinder, to the distilling chamber, so that, by means of the natural embedding of the biiquettes in the ciiider the desired insulation is obtained. `Even if some of the individual briquettes touch the wall, this contact, due to the egg-shape, only occurs on an infinitesimal surface, so that'the danger of scoriication is, to say the least, very greatly diminished. The

- same idea, however, can be still further perfected by using large rectangular briquettes made of zinc ore and cinder, and formed outside the oven structure into a ycake of somewhat smaller dimensions than the inside measurements of the oven chambers; this cake 5 is then introduced into the oven, similarly to the tamped cake in coking'certain kinds of coal, while the space which remains between the cake and the oven wall is subsequently filled with cinder loosely introduced fromv above. In this manner there is obtained a completel enveloping of the Vcharge proper with pure cinder; thisv produces the advantage-at the same time that the heating gases that may leakthrough untight places in the walls, can only come in contact with the zinc ore in reducedform.

In the accompanying drawing a form of 5o oflline IiP-IV, Fig. 2.

Referring to said drawings, the chamber a is charged from above through the charging-openings b with the aid of the charging car c, and is emptied after the reduction is accomplished, through the doorway infront of the chamber a after-the door e on the front side of the chamber has been removed by means of the movable door handling device d. The choke damp developing during discharge through the doorway is carried away through a chimney f, while the ashes drop into a receptacle g lined in a fireproof manner, from which they can be discharged, as may be required, by lifting the slide 7L, into the receptacles i. Through'the ports c of the From the rear wall of the chamber the gases Vaporizable at low and high temperatures that were 'by the flowing downward from above of the zinc vapors, because this creates the most advantageous conditions for the requisite difference in temperature.

The chamber a is built up, similarlyto la coke oven chamber, of ireproof molded bricks and enclosed between two heating walls Q each, which themselves are again divided into and constituted of individual flame heating y flues p; (Fig. 2) each of the flame .flues is provided with one feedg for air and one feed r for gas (Fig. 3) andthe hues can be further regulated for flow atntheir upper termination into the collecting channels by means ofslides t. In this manner an entirely uniform heating of the walls is rendeied possible, av regulating manipulation being feasible at any point. Below the chambers a and `the heating walls 0, the regenerators u and o are arranged which are provided with a connection for communication-with the waste heat channels 'w and the gas conduits m, or a connection with the outside air, in alternation. The operation of these regenei'ators is as customary y -in that all the chambers of one side are preheated by absorption of waste heat of exhaust gases from one half of the heating flues, while the heated fuels, gas and air, pass through the other regenerator chambers to be preheated by absorption of heat from 'the-regenerators; after half an hours time areversal takes place in thedirection of the draft, which results in the regeneratois alternating in their tasks of'absorbing and imparting vheat from and to gas. O n account ofthe fact that each chamber has its own regenerator, it is possible to influence each chamber as a wholein regard -to the heating, notwithstanding the structural unity of a series of such chambers. The assembling of the individual chambers into one building block or battery, as is well known,

not only commends itself for structural reasons, such as a saving in space, but also with reference to the diminished losses caused by heat radiation and the like'.

In operating the oven structure for Vreducing zinc and similar volatile metals, the chambers a are'` constantly mail itained at a high temperature sufficient to latilize concurrently both lower` and higher boiling point fractions of charges within the respective and the condensing channels Z discharge the y ranged side-by-side; heating walls comprislower'. boiling point volatilized fractions, of the gaseous admixtures from the ports lo of the respective chambers a, in gaseous form andthe higher volatilized' fractions thereof in liquid form.

What is claimed is y 1. An oven structure for reducing zinc and similar volatile metals comprising, in combination: parallel. distilling chambers aring individual and separately regulable vertlcalliame-iues between and contiguous to said chambers andregenerators connected with ,said flame-lines, for heating said chambers uniformly and for substantially constantly maintainingthem at a high temperature suflici'ent to volatilize concurrently both low boiling point fractions and high boiling point fractions' from material within said chambers; fftake means communicating with each of said distilling chambersl for olf-'flow of low and of high boiling point fractions together and in gaseous adinixture from therespective chambers; and condensing channels integral with said oven 'structure and communicating with the offtake means of the respective chambers for receiving said frac-` tions in gaseous admixture therefrom, and adapted to discharge the lower boiling point fractions thereof in gaseous form and the higher boiling point fractions thereof in liquid form; whereby said distilling chambers may be uniformly heated'to maintain them at substantially the same constant high temperature during the volatilization of both point fractions Iof lower and higher boiling charges therein.

2. An oven according to claim 1, characterized by the regenerators which form a uniform Whole with the oven plant, being divided as described, into individual groups,

so that eachchamber, regardless ofv its structural connection with the others, can be operated and regulated as an independent unit.

3. An oven according to claim l, characterized by the condensing channels respectively comprising a narrow space provided at the rear side ot' one of the oven chambers and regenerators, and cooled by surrounding cooling channels, the lZinc vapors entering this space being liqueiedinto metallic zinc therein while falling downward from above.

4. An oven for the reduction of zinc ore, constructed with .distilling chambers built side by side with intervening heating chambers and walls, and regenerators in pairs connected with said heating chambers, each set of regenerators communicating with only one heating chamber, and condensing chambers for the zinc vapors connected with said distilling chambers.

5. An oven for the reduction of zinc ore, consisting-of a unitary built-up structure containing distilling chambers arranged sidel by side with intervening-heating chambers and walls, and regenerators connected with said heating chambers and having air and gas supplying means, and condensing chambers for the zinc vapors connected with said distilling chambers.

6. An oven for the' reduction of zinc ore, consisting ofv a unitary structure containing distilling chambers arranged side by side with intervening heating chambers and Walls, and regenerators connected with said heating chambers and having air and gas supplying means, and narrow channels for the Zinc vapors and cooling channels alternating with said narrow'channels.

' HEINRICH KOPPERS.

Images