US1731898A - Treatment of ores and metallurgical products - Google Patents

Description

Oct 15, 1929.

H. G. HEINE TREATMENT OF ORES AND METALLURGICAL PRODUCTS Filed A i-n 23, 1927 2 Sheets-Sheet 1 Fig. 1

Oct. 15, 1929. H. s. HEINE 1,731,393

TREATMENT OF ORES AND METALLURGICAL PRODUCTS.

Filed April 23, 1-927 z sheets-sheet 2 Mvenforr:

.the section of the kiln Patented 0a. is, 1929 UNITED STATES PATENT OFFICE GERMANY, ASSIGNOR T0 FRIED. KRUPP OF MAG-DEBURG-BUCKAU, GERMANY 'I'REATMEN 0F ORES AND METALLURGICAL PRODUCTS Application filed April 23, 1927, Serial No. 188,053, and in Germany April 28, 1926.

My invention relates to a process of volatilization of metal in the form of metal fume or in the form of oxidic compounds or compounds containing chlorin or sulphur, or admixtures of such in reverberatory furnaces i. e., rotary kilns. In processes of this kind it is of importance that the temperature in the furnace shall rise uniformly from the charging end up to the main reaction zone and shall be maintained in this zone as long as possible at the same degree for the purpose of attaining as complete a volatilization as possible and to avoid an agglomeration or fusion in the main zone of reaction.

The object of my invention is to maintain an even maximum temperature during a period of greater length. I propose to reduce (temporarily or permanently by steps) the transverse section of the furnace, for instance of a rotary kiln in the direction of the travel of the material.

The accompanying drawings show diagrammatically apparatus for carrying out the process.

Fig. l is a section of a furnace containing one step built of bricks;

Fig. 2 is a section of a furnace containing several brick steps of gradually increasing height;

Fig. 3 shows a different arrangement of several steps arranged for a process which is carried out in two stages, for instance a calcination stage followed by a volatilization stage; and

Fig. 4 shows a furnace containing a step built up by fusing to the wall of the furnace a ring of the material to be treated.

In the drawings a is a rotary kiln of the usual type, Z), 6 b b b b and 6 represent steps constructed of brick or similar material, while 6 represents a step built up by fusing to the wall of the furnace a ring of the material to be treated, and 0 represents the material undergoing treatment. l5

As required one may provide one or more steps and it may be of advantage to enlarge after one, or several steps. The steps can also be formed during the treatment by burning in the material which forms ring-shaped deposits on the lining owing to the rotary movement of the kiln. In this way the position of the steps in the furnace may be changed ad libitum by varying the point to which the heating flame is directed for instance according to the always varyino composition of the material to be treate By the use of such steps by means of Which the section of the kiln is reduced, the material travelling through the furnace'is retarded in such a way, that in front of such a step a layer of gradually increased depth is forn'ied in the kiln. As a result the heating of the material in front of the step by the heating gases is lessened because a greater surface of the charge is in contact with the cooler lining, while the surface of the charge exposed to the heating gas, relative to the entire mass of the charge, is considerably reduced. By reducing the surface a slowing of the chemical exothermic reaction is attained. In this way it is possible by choosing the height and number of the steps to form zones of even temperature inside of the kiln.

In the application of this invention to the volatilization of zinc, the zinc-bearing material, mixed with reducing material, is charged at the upper end of the furnace, and in consequence of the turning and the inclination of the furnace it slowly progresses along the furnace. The effect of a heating flame or of the combustion of the reducing material slowly heats the material up to the point where reduction and volatilization begin.

In consequence of the action of the heating flame the material is either gradually so overheated that it melts, or, if care is taken to raise the temperature so slowly that no melting takes place, the zinc only begins to volatilize shortly before it reaches the hottest part of the flame and the material leaves the furnace before a complete dezincing has been attained.

According to the present invention one or more steps are built up near the discharge end of the furnace so that the material piles up to the height of the steps. This piling up causes a change in the relation of the volume to the exposed surface of the layer of material. The cooling effect of the endothermic reaction taking place in the interior of the layer of material is therefore no longer ex ceeded by the heating effect at the surface and.

by proper choice of the position and height of the steps these efiects can be exactly compensated. .In this way it is possible to maintain a zone of relatively high, but uniform, tem-' perature in the furnace, and to carry out the deslred volatilization to an essentially complete degree, without fear of overheating the material with'a resulting melting or sintering. -Various changes and modifications may be made in the design and the structural details of the rota furnace used consistent with the nature 0 the material to be treated, and

- in'the respective steps for obtaining the best 'ble results by my improved process without substantially departing from the spirit ofthis invention. v

Having now particularly described and ascertained the nature of my said invention and-in what manner the same is to be performed, I declare that what I claim is:

1. Aprocess; for recovering volatilizable metals from ores, metallurgical products and residues, by subjecting said materials to the action of heat in a kiln which comprises forming zones of uniform temperature of reaction within the kiln by locally reducing the transverse section of the kiln so that the height of the layer ofmaterial is varied.

2.. A process as claimed in claim 1 wherein the local reductionoi the transverse section I of thekiln is eflected by means of steps.

'3. A process as claimed inclaiml wherein the local reduction of thetransverse section of the kiln is efiected by means of a plurality gliteps arranged at various laces within the 1m this 11:

The forei ing specification signed at Ber- .day of fi'il, 1927'. HANS G HARD HEINE.

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