US2369029A - Smelting of nonferrous materials - Google Patents

Description

reams Feb. e, 1945 UNITED STATES PATENT OFFICE SMELTING F NoNr'nanoUs MATERIALS Louls-S. Deitz, Jr., Westfleld, N. J., and Walter H. Jacobson, Tottenvllle, N. Y., assignors to Nassau smelting & Refining Company, Incorporated, New York,'N.*Y., a corporation of New York No Drawing. Application December 14, 1943, Serial No. 514,274

15 Claims. (Cl. 75-24) This invention relates'to the smelting of nonferrous materials and more particularly to the production of copper base products containing substantial quantities of tin by treating nonferrous materials and secondary metals in a blast furnace.

It has been customary to smelt various mate- In accordance with one embodiment of the in vention, a blast furnace is charged with materials containing copper and other non-ferrous metals,

together with the usual slagging and reducing materials, and the materials are smelted. As part of the charge, there is introduced zinc-bearing material, suchas scrap brass, and tin-oxide rials containing copper and one or more of the trlcal equipment, machine'shop turnings, grindings and sweepings, punch press scraps, and various croppings, trimmings, residues, drosses, skimmings, slags, ashes, etc., such as are produced in smelting, refining, plating and other operations.

The materials produced by such a procedure have a low tincontent and usually contain not more than about 5% of tin.

It has not been the practice to use high grade secondary tin materials and residues, or to include tin ores in blast furnace charges of this type. The reason for this is that, from past experience, it would be anticipated that a, substantial amount of the tin would be lost in the slag and, more important still, that an excessive amount of the tinwuld'beflrivenofl'asinme or dust particles, which would be collected inthe flue dust, along with other materials, such as zinc oxide. The flue'dust would have to be reprocessed to recover the tin found therein and this 'would increase considerably the cost of the process.

As a result, when it was desired-to produce a copper base alloy containing substantial quantities of tin, the usual procedure was to smelt materials of the type referred to, thereby producing a low tin material, then to treat this material in a reverberatory furnace, along with other materials, and finally adding pig tin in the proportions necessary to obtain an alloy of the required composition. Since the supply of pig tin is limited and the use thereof is restricted, it is desirableto employ processes in which the tin required may be supplied from secondary sources or from tin ores.

An object of this invention is to provide new and efl'ective processes for smelting non-ferrous materials.

material, such as high tin drosses and tin ores, with the zinc-bearing material preferably beneath the tin-oxidematerial so that the zinc vapors producedwill permeate the tin-oxide material and reduce the tin therein to metallic tin.

This process is based on the. observation that, when metallic zinc and tin oxide are heated to a temperature above the melting point of copper, the zinc reduces the tin oxide to metallic tin and the reaction proceeds exothermically. This indicates that zinc could be used as an active reducing agent for tin oxide in metallurgical processes, such as those employed in blast furnace smelting operations because the heat of reaction tends to accelerate the reaction. From this observation it was conjectured that, if brass or other alloy or mixture of copper and zinc (with or without the presence of other materials, such as lead) is heated with tin oxide to the temperature of reaction, the zinc should reduce the tin oxide to metallic tin, which would immediately alloy with the copper. Experiments have demonstrated that this process may be used with extremely satisfactory results on a commercial scale and in commercial blast furnaces, and that it provides an economical .and readily controlled means of producing high tin blast furnace pigs of predetermined compositions.

Under normal blast. furnace, conditions, the coke or other carbonaceous reducing material that is present in the charge, as well as the reducing gases derived therefrom, will reduce a.

considerable portion of the='tin oxide and other metallic oxides inthe charge. The zinc present in the charge employed in processes embodying this invention will insure the reduction of any tin oxide not otherwise reduced in the furnace.

The advantages of such a process are that the metallic, tin produced is taken up by the copper and is not volatilized, the slag contains ,very little tin, and tin-oxide materials containing high percentages of tin may be used to build up the tin content of the resulting product without excessive loss of tin. This process permitsthe use of high tin drosses and ores, which formerly were not treated in blast furnaces. and results in products having high tin contents without the use of metallic tin.

The above-described and other objects and features of the invention will be apparent from the followingdescription of specific examples of processes embodying the invention, which are given by way of illustration and not to limit the scope of the invention.

Example I terials, such as coke, sand, limestone and iron oxide, and smelting the charges. Several of such charges were fed into the furnace, one. on top of another, and as the several charges were smelted additional charges were fed into the furnace.

The ingredients of each charge were introduced into the furnace in such order that the zincbearing materials were below the high tin dross in each charge. As a result, the zinc volatilized from the zinc-bearing material in a given charge passed upwardly through the tin dross and reduced the tin' oxide therein, which was not otherwise reduced, to metallic tin, which alloyed with the molten copper that passed through the charge nace in the order named:

Approximate composition Pounds added Material Per cent 8n Per cent Per cent Cu Pb Coke Low lead reverberatory slag"; Copper ashes Low lead rev Irony tailings Brass and bronze scrap. Copper-clad steel wire. Copper ashes Telephone ringer coils Yellow brass t s Telephone repeater coils. Tin plate dross T impsl'nna .Iron S0319 The tin dross was mixed with a small quantity of lime and water to produce a pasty mass which could be readily handled and to retard volatilizetion or mechanical dusting of the tin. If desired, the tin-oxide dross can be added in the form of briquettes, in which the dross is held together by a bituminous material or Portland cement. In any event, it is desirable to mix with the tin dross a material which retards volatilization or mechanical dusting of tin.

It will be observed that each charge contained previously known methods.

approximately 6000 pounds of raw material from. which were-obtained approximately 2500 pounds of metal in the form of blast furnac pigs containing 79.5% of copper, 10.8% of tin, and 1.95% of lead, with the balance being chiefly zinc but also including impurities, such as iron, nickel, antimony and sulfur. The slags produced were analyzed and were found to contain about 0.5? of copper and less than 1% of tin.

Thus, it will be 'seen that by the introduction of high tin dross material into a blast furnace charge of a type that would normally produce a pig containing less than 5% of tin, the tin content of the pig is more than doubled and only a small quantity of tin is lost in the furnace slag. This process, therefore, provides a ready means to utilize a tin-containing material which had been difllcult to treat to recover .the tin values therein by previously known methods. This dross contains a substantial quantity of iron, which makes it unsuitable for use in a reverberatory furnace, but, because of the high tin losses experienced in the normal blast furnace operations, it had been uneconomical to treat such material in blast furnaces to recover the tin therefrom. Another reason why this materi'alcan be successfully used in a blast furnace charge of the type described is that iron is usually included in such charges to help slag out some of the impurities, and the iron present in this high tin dross assists in the slagging operation.

It is possible to produce blast furnac pigs containing considerably more than 10% of tin by adding to charges of the type described larger quantities of high tin drosses and making certain that the zinc content of the charge is sumciently high to insure substantially complete reduction of the tin oxide contained in the tin dross. Thus, in specific runs of this nature in which higher quantities of tin dross were added, blast furnace pigs of the following approximate compositions have been made:

Composition of pigs Charge Per Per Per Per Per P t cent cent cent cent cent Cu Sn P Fe Ni 3. 26 2. 0 0. 5 Balance 3. 15 2. 0 0. 5 D3. 4. 29 2. 0 0. 5 D0. 3. 02 2. 0 0. 5 D0. 3. 00 2. 0 0. 5 DZ).

Two similar charges to which no tin dross had been added produced blast furnace pigs containing 83.89% of copper, 4.74% of tin and 5.43% of lead and 83.61% of copper, 2.9% of tin and 6.3% of lead, respectively. This illustrates forcefully that by practicing processes embodying this invention, it is possible to produce blast furnace pigs containing from two to at least five times as much tin as is prment in blast furnace pigs manufactured in accordance with the procedures formerly employed, without the introduction of any virgin tin. At the same time, the tin value is recovered from a product which was difllcult to process by Example I] In accordance with this process, materials similar to those included in the charges described in Example I were used, but instead of adding high tin dross to provide the tin necessary to build up the tin content of the blastfumace pigs, tin, ore was employed. One specific type-of charge,

in which tin ore was employed, consisted of the following materials fed into the furnace in theorder named:

Approximate composition Material Per cent Per cent Per cent Cu Sn Pb Coke Flue dust i Red metal dump slag... Low lead reverberatory furnace sl Brass and bronze skimmings Irony brass turnings Cogper ashes e Irony brass Manganese bronze tumss Telephone ringer coils- Light brass Broken silica brick Copper bearing turnings Iron scale Limestone Bolivian tin concentrates From each charge of this nature, there were obtained approximately 2500 pounds of blast furnace pigs analyzing 80.14% of copper, 10.5% of tin and 2.5% of lead. The slag was analyzed at intervals during the run and was found to contain from about 0.5% to about 1% of tin.

Obviously, if it is desired to increase the tin content of the blast furnace pigs, this can be accomplished by increasing the amount of tin ore added to the, charge and making certain that the charge contains enough zinc to insure substantially complete reduction of the tin oxide in the ore. bearing material in the charge was fed into the furnace before the tin'ore was introduced therein in order that the zinc volatilized would perme.. ate the tin ore and efiectively reduce the tin oxide therein. The tin ore may be introduced in the charge in the form of briquettes or mixed with lime and water.

It has been diflicult to utilize certain tin ores, because of the relatively high percentages of impurities and the types of impurities, such as iron, found therein. In fact, it is usually necessary in smelting such ores to mix tin ores of the type obtained in Malaya therewith in order to process such ores economically. The process embodying this invention provides a means for utilizing these impure ores with a substantially complete recovery of the tin values therein, and without having to mix them with other higher grade ores, such as the Malayan type ores.

Obviously, the invention is not limited to the use of the specific high tin drosses and ores recited in the specific examples given hereinabove, but the processes embodying the invention may be practiced with satisfactory results with the use of other tin-bearing materials containing substantially large percentages of tin oxide. By carrying out the processes in such manner that the blast furnace charge always contains enough zinc to complete the reduction of the tin oxide in the tin-bearing material employed, especially when the materials making up the charge are fed into the furnace in such order that the zincbearing materials are beneath the materials containing the tin oxide, a commercially complete reduction of the tin oxide is obtained and the losses of=tin in the furnace slag and the amount of tin appearing as a constituent of the flue dust are sufficiently low to make the process comin the usual blast furnace operations general nature.

mercially feasible. Another feature of the invention is that the amount and types of reducing and slagging materials used in these processes are not materially different from those employed of this What is claimed is:

1. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including copper, zinc and tinbearing materials, and smelting the charge, at least a subst ntial part of the tin-bearing material' being material .of the class consisting of high tin content dross and tin oxide ore and the zinc-bearing material being present in suflicient quantity to insure substantially complete reduction of the otherwise unreduced tin-bearing material to metallic tin.

2, The'process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including copper, zinc and tinbearing materials, introducing the constituents of the charge into the furnace in such order that the zinc-bearing material is beneath the tinbearing material, and smelting the charge, at least a substantial part of the tin-bearing material being material of the class consisting of high tin content dross and tin oxide ore and the As in the previous example, the zinczinc-bearing material being present in sufllcient quantity to insure substantially complete reduction of the tin-bearing material to metallic tin.

3. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including copper-bearing and rials, which comprises introducing into a blast stituents of the charge being introduced into the furnace in such order that the zinc-bearing material is beneath .the tin oxide material whereby the zinc vapor produced passes upwardly through i the tin oxide material and reduces a substantial quantity of the tin oxide to metallic tin.

5. The process of smelting non-ferrous materials, which comprises successively feeding into a :blast furnace a plurality of like charges including copper-bearing and other materials containing metal of the group consisting of lead, zinc and tin in such proportions as to produce a pig metal consisting of upward of 70% of copper, including in each charge a substantial quantity of zinc-bearing material and tin oxide material containing upward of 40% of tin, and continuously smelting the charges, the constituents of each charge being fedinto the furnace in such beneath the tin oxide material whereby the zinc volatilized therefrom passes upwardly through ,the tin oxide material in that and succeeding charges and reduces to metallic tin a substantial 6 quantityof tin oxide which otherwise would be unreduced.

6. The process of smelting non-ferrous materials, which comprises introducin into a blast furnace a charge including material containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material being a material havin a high tin oxide content and theamount of zinc-containing material in the charge being sufflcient to reduce a substantial quantity of the tin oxide to metallic tin.

7. The process of smelting non-ferrous mate rial, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material being a high tin oxide content dross and the amount of zinc-containing material in the charge being suflicient to reduce a substantial quantity of the tin oxide to metallic tin.

8. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material being a high tin oxide content ore and the amount of zinc-containing material in the charge being suiiicient to reduce a substantial quantity of the tin oxide to metallic tin.

9. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material being a tin oxide material having a tin content of upward of 40% and the amount of zinc-containing material in the charge being sufficient to reduce to metallic tin a substantial quantity of the tin oxide which otherwise would remain unreduced.

10. The process of smelting non-ferrous mate- ,rials, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material .bein a tin plate dross containing at least 40% of tin and the amount of zinc-containing material in the charge being suflicient to reduce a substantial quantity of the tin oxide to metallic tin. I

11. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smeltingthe charge, at least a substantial part i of the tin-containing material'being a tin oxide ore containing at least 60% of tin and the amount of zinc-containing material in the charge being suflicient to reduce a substantial quantity of the tin oxide to metallic tin.

12. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including materials containing copper, zinc and tin, and smelting the charge, at least a substantial part of the tin-containing material being a tin oxide metal having a tin content of upward of 40% and the amount of zinc-containing material in the charge being sufficient to insure substantially complete reduction of the tin oxide which otherwise would remain unreduced, said material containing tin oxide being mixed with a .binder before being introduced into the furnace to diminish mechanical losses of tin.

13. The process of smelting non-ferrous materials, which comprises introducing into a .blast furnace a charge including carbonaceous reducingmaterial and copper, zinc and tin-bearing materials, and smelting the charge, the metalbearing materials in the charge being present in such proportions as to produce a pig metal consisting principally of copper and having a tin content of more than 5%. a substantial part of the tin-bearing material in the charge being inaterial of the class consisting of high tin content dross and tin oxide ore, the zinc-bearing material being present in suflicient quantity to insure substantially complete reduction of the otherwise .unreduced tin-bearin material to metallic tin.

14. The process of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including copper-bearing and other materials containing metal of the group consisting of lead, tin and zinc in such proportions as to produce a pig metal consisting of upward of of copper and substantially more 4 than 5% of tin, including in the charge a'substantial quantity of zinc-bearing material and material having afhigh tin oxide content, and smelting the charge, whereby the zinc vapor produced reduces a substantial portion of the tin oxide to metallic tin.

15. The method of smelting non-ferrous materials, which comprises introducing into a blast furnace a charge including copper and tin-bearing materials and other materials containing non-ferrous metals in such proportions as to produce a pig metal consisting principally of copper and containing substantially more than 5% of tin, including in the charge a substantial quantity of a high tin oxide material having a tin content of upward of 40% and suflicient zincbearing material to insure substantially complete reduction of otherwise unreduce'd tin oxide in the charge, and smelting the charge.

LOUIS S. DEI'IZ, JR. WALTER H. JACOBSON.