US2408278A

US2408278A - Process of metal recovery

Info

Publication number: US2408278A
Application number: US585816A
Authority: US
Inventors: Philip T Stroup; Charles B Willmore
Original assignee: Aluminum Company of America
Current assignee: Howmet Aerospace Inc
Priority date: 1945-03-30
Filing date: 1945-03-30
Publication date: 1946-09-24
Anticipated expiration: 1963-09-24

Description

Patented Sept. 24, 1946' PROCESS OEMETAL mioov aY; Philip '1. Stroup and Charles 'B; 'Wil1more, New "1 .Kensington, Pa., assignors-to Aluminum Com-1 pany of America, Pittsburgh, Pa., a corporation:

of Pennsylvania 7N0 Drawing. Application March so, 1945.

Serial'No. 585,816 6Claims. (or; 75-67) This invention relates to those processes of metal recovery in which a gas-vapor mixture containing carbonmonoxide and a vapor or a metal miscible with molten aluminum is passed into contact with a body of molten aluminum for the purpose of condensing and absorbing the metal of the gaseous mixture and thereby effecting separation between the metal vapor andthe carbon monoxide and other non-metallic components of the gas-vapor mixture. v

Such a process is particularly useful when it is desired to obtain metals, uch as zinc '01 magnesium, directly. from their 'oxidic'ores by heating said ores with carbon ofabarbonaceous substance at temperatures in excess of the boiling point of the metal to be recovered. In such cases the process tends to be reversible and if immediate and complete separation'is not achieved be-' tween the gaseous products of reaction, which include the metal vapor and the carbon monoxide, the CO will react with the zinc or magnesium vapor to again form the oxide of the metal and thus prevent the desired recovery of the metal. Molten aluminum is a valuable medium for effecting the. desired separation, not only because of its miscibility with zinc or magnesium, but also because it forms with'either of those metals a .useful series of commercial alloys and it'is thus possi=b1e .to produce directly by, the separation or absorption process a usable. product which, if desired, may be utilizediwithout further processing by distillation or'other familiar step, to separate the dissolved metal from the aluminum.-

Whenever a body of molten aluminum is used as amedium by which a metallic vapor, is condensed and separated from a gas-vapor mixture which contains the monoxideof carbon'there is formed, as a result of contact between the alumi num body and the carbon monoxide, asludge or dross which causes serious mechanical handling difficulties and also tends to contaminate the alloy which is the product of theoperations. This sludge or dross contains metal carbides, metal oxides and carbon. It is usually of great volume in relation to its weight and, if not controlled, may form with such rapidity and in such volume as to mechanically impede and clog the vessel or chamber in which contact between the gas-vapor mixture and the molten aluminum body is established. V 1

It is the object of this invention to eliminate, or substantially impede, the formation of this S u e or dross during the above described operation and we have found that the presence in the molten aluminum body of certain metals in relav 2 tively minute quantities will achieve this object in substantial degree. 1 In accordance with our invention the objects above mentioned are attained by adding to the molten aluminum a small amount of beryllium and manganese; I The result of .this addition. is a substantial reduction in the rated formationfof the aforesaid sludge or dress and, in some'ob-I served cases, a substantially. complete pri'avention of any. dross formation. I Best results have been? observedwhere the temperatureof the molten aluminum absorbingbodyis not much in excess of about 100 .C. above themeltin'g point of the aluminum, and we prefer'tomaintain the molten absorbing body at a temperature within, about 125 C. of its melting point, which pointwi'll, of: course, vary dependinguponthe amount oimetal' vapor which has been. absorbed by the aluminum from the gaseou mixture of metal vapor/and carbon monoxide with which it iscontacted. The above described effect of the presence of the beryllium and mang'aneseflinthe molten aluminum body is observable when the manganese'is present in amounts within the range of, about:0.1 to about 1.0 per cent by weight of the molten absorbing body and the beryllium is present in amount within range of about .005 to 0.5 per cent by weight of said body.. Thepresence of these elements inselected specific concentrations with:

in these expressed ranges will, insome cases, give.

better results than will other'speci'fic concentrations but usually the best results haveiap peared when the. beryllium is in the range'of about 0.0075 to 0.02 per Centand the manganese is in the range of about 0.2 to about 0.5-per cent.

Simple. experimentation within the indicated ranges will readily disclose the best amounts in which these elements may be present 'under 'a given set of operating conditions'du'ring theabsorption of the vapor of a metal which ismiscibla with the molten aluminum absorbing'b'ody...

For instance; in vapor from a mixture of magnesium vapor and carbon monoxide it appears that, in general, the best combination of beryllium and manganese in the molten aluminum absorbing body is that of about .01 per cent by weight of beryllium and 0.2 per cent by weight of manganese, but if the absorbent already contains a relatively large amount of magnesium, say over about 20 per cent by weight, it may be preferable to use higher amountsof manganese up to 1 per cent. In one instance we have observed the presence of 0.01

Per cent by. weight of beryllium and 0.2 per cent by weight of manganese to practically prevent the abgdrpnbn bf magnesium" all formation of dross during the absorption of ever, substantial efiects are not produced-unlessthere are concurrently present both beryllium. and manganese. The manner in which the mane-.- .ganese functions in the molten' aluminum body is obscure. Analyses of the molten aluminum body before and after contact: with: substantial. amount of carbon monoxide show that theresi'sz no appreciable change in concentration of. man ganese during the period. of contact between the molten aluminum body and the gaseous reaction mixture. Hence, weassume that the function of the manganese may be that oia negative catalyst. Inany event, however, best results are obtained when. the. manganese and the beryllium are both present. in the moltenaluminum absorbing body.

The effect. of the beryllium and manganese is, of. course, not limited to a condition where the molten absorbing body. is entirely composed of aluminum. In the pr'ocessof the general nature herein described it is often convenient to use a molten absorbing" body;. a portion of which is composed. of the metal the vapor of which is to be absorbed or of a metal different than the metal" vapor which is to be absorbed. However, so long as the molten. aluminum absorbing body principally composed of aluminum in the sense that it exhibits the characteristics of molten aluminum to react with carbon monoxide to form the dross in question, the presence of beryllium and manganese in the molten body'will'be beneficial in reducing or eliminatingthe tendency of. the aluminum inthat' body to react with the'carbon monoxide to form a dross.

The manner inwhi'ch the gaseous mixtures of. metal vapor and carbon monoxide are contacted with the molten absorbing body forms no part of this invention. The. two. classic methods of. achieving this contact. are to pass the gaseous" mixture through the molten absorbing body or to pass the. gaseous mixture over the surface of the molten absorbing body. The choice of either of these or other methods of contact are usually dictatedby' the" practical aspects of the viding said aluminum body with a content of beryllium and manganese, the amount of said beryllium being about 0.005 to 0.5 per cent by weight of said body and the amount of said manganese being about 0.1 to 1 per cent by weight of said body.

2.. In a process of metal. recovery in which a gas-vapor mixture containing carbon monoxide and a vapor of a metal miscible with molten aluminum is contacted with a molten aluminum body and vapor of said miscible metal absorbed in said body, the improvement consisting in providing said: aluminum body with a content of beryllium-and. manganese, the amount of said beryllium'beingabout 0.0075 to 0.02 per cent by weight of said body and the amount of said manganese-being about 0.2 to 0.5 per cent by weight of. said body.

3.11:1. a process of metal recovery in which a gas-vapor mixture containing carbon monoxide and a vapor of a metal miscible with. molten aluminum is contacted with: a molten aluminum body and vapor of said miscible metal absorbed in said body, the improvementconsisting inprovidi'ng, saidaluminum body with a content of beryllium, and manganese, the amount of said beryllium being. about; 0.005 to 0.5 per cent by weight of said bod'y'and the amount of said manganese being about 0.1 to 1 per cent by weight of said body, and during said process maintaining said molten body at. a temperature within C. of its melting'point.

4. In a process. of recovering magnesium. in which a gas-vapor mixture containing carbon monoxide and magnesium vapor is contacted with a molten aluminum body, the improvement consisting in providing said aluminum body with. a content. of beryllium and manganese, the amount of said beryllium being about 0.005 to 0.5 per cent by weight of said body and the amount. of said manganese being about 0.1 m1 per. cent by weight of said body.

5. In a. process of recovering, magnesium in. which a gas-vapor mixture containing carbon.

' monoxide and magnesium vapor is contacted with a molten aluminum body, the improvement-consisting in providing said aluminum body with a. content of beryllium and manganese, the amount of said beryllium being about 0.0075 to 0.02 per cent by weight of said body and the amount of said manganese being about 0.2 to 015 per cent by weight of said body.

6. In a. process of recovering magnesium in which a gas-vapor mixture containing carbon monoxide and magnesiumvapor iscontacted with a molten aluminum bod'y,., the improvement consisting in providing said aluminum body with about 0.01 per cent by weight of beryllium and 0.2 per cent byweight of manganese.

- PHILIP 'r. STROUP.

CHARLES B. WILLMORE.