USRE17347E - Daniel gushing - Google Patents

Description

D QJSHNG 'Y Re. 1,7,34'1

raocsss FonK mamme Ann RErlxIpGpF nourannous METALS neiaaea July 2, 1929.

UNITEo STATESPATENT OFFICE.

DANIEL cUsHING, or GAMBEI'DGE, MASSACHUSETTS, AssIeNon To THE BARRETT COMPANLA CORPORATION or NEW: JERSEY.

VPROCESS FOB MELTING AND REFINING OF NONFERROS METALS.

Original No. 1,556,591,

Heretofore the melting` of non-ferrous metals and their alloys has been accomplished in a variety of ways either for thepurposeof purifying' them or modifying their charac- `teristics or treating them with other substances or merely for the purpose ofgetting them into a liquid state so that they could be poured into molds or cast into ingots.

One of the most common methods of melt- '10 ing 'such metals ortheir alloys is to introduce them into4 crucible furnaces that are heated from the Voutside Vby using gas, oil, coal, coke or other fuels.' Objections and difficulties often arise because the crucibles are expensive and differ in characteristics; the heat from the fuel must be transferred through the walls of the Crucible to the material inside thusmtreducing the thermal efficiency and causing high fuel costs; and, due to the fact that v each crucible is necessarily of comparatively small size, a large number are required Where large castings are to be produced.

' When reverberatory furnaces are used for melting metals the fuel cost is higher than it Would be if the material to be melted were in direct contact with incandescent-fuel, and it is diicult to control the operations which require skilled operators and careful manipulation and in these furnaces the flexibility a to tonnage cast is limited. Electric furnaces are also sometimes used for this purpose but entail large cost for power and great expense for installation and repair.

It has been known for a long time that 'cu pola furnaces afford the cheapest means of melting iron because of the'direct contact be-4 tween the metal and `fuel with a cdrresponding maximum absorption of heat. At the same time such units can be built and operated in various sizes, are easily controlled, and the same furnace can be charged with charges of different sizes at diiferent times. While cupolas are commonly used for melting iron theyhave not proven satisfactory for `the reasons, among which may be mentioned the followingz-non-ferrous metals absorb sulfur from the fuels; the heavy blast of air commonlyused in such furnaces for iron causes the formation of metallic oxides which, commelting of non-ferrous metals for.several dated October 13, 1925,`Sral "110. 679,107, filed December 7, 1923. Application for reissue led October 12, 1927:,V Serial No. 225,829.

batches of fuel from the same source are sufficiently different from eachother as to cause difficulty and require constant exercise of dil igence in order to obtain an approximately correct'and proper control of the gases and of the slag; and some non-ferrous metals,.such as those containing zinc for example, suii'er great losses from volatilization in the ordinary cupola furnaces.

Pv the present invention difficulties and 0b jections o f prior knownmethods have been overcome and non-ferrous metals have been readily and satisfactorily melted in a cupola furnace''in a rapid and eiiicient manner Without great loss of material.

One f the lfeatures that has contributed to the successful development of my invention is the selection of the right sort of fuel, o1' a fuel having the proper characteristics, for' melting non-ferrous metals or their alloys in' a cupolafurnace. I have found that a fuel- Will operate satisfactorily for'this purpose if it'has sufiicient mechanical strength or resistance to crushing to enable'it tosupport a cupola charge, provided -it is at the same time l substantially'free from sulfur and asmh and and other deleterious materials and also pos- 'sesses sufficient thermal capacity, or sufficient B. t. u. per pound, to enable it to develop the requisite amount of heat'without necessitating such a strong air' blast that an excessive oxidizing atmosphere is present in the furnace. An example of such a fuel is the coke obtained vfrom coking coal tar pitch in a bee hive oven. This vcoke is mechanically strong, consists'of about 98% to 99%of fixed carbon, is substantially' free from sulfur 'and ash, has no phosphorous and posesses about 14,500 B. t.` u. perpound.

In carrying out' this invention I may use a cupola furnace similar to those already in common'use in which the metals are laid on the coke or layers of metal and coke alternate and the combustion is maintained by the introduction of air through tuyres near the 4bottom of the furnaces. By restricting the ingress of air it has been found that sufficient combustion can be maintained so that the metals can be melted and at the same time a reducing atmosphere can be malntamed near the metalso that excessive oxidation can bev When the metal is melted it may be withdrawn from the cupola in the ordinary manner into a ladle, run into molds, cast into ingots, or otherwise disposed of by using spe. cial reservoirs, pouring devices or casting machines.

This invention has been found applicable to the melting and purification of a very large number of non-ferrous metals and their alloys, for example, such as copper, nickel, aluminum, tin, antimony, lead and zinc. The invention will be more specifically and particularly described in its application to the melting of copper and of bronze in a cupola furnace but it-is to be understood that it is not to be restricted to the melting of, these particular metals or to this particular type of furnace. l

i In practising, this invention I may elmploy cupola furnace such as is illustrated in the accompanying drawings in which Figure #l I isan elevation and Figure #2 is a plan view partly in section. f Y In the drawings, reference eharacterl desu ignates a cupola'that may be mounted'on a measuring the same; The branches 6 each the like and the zcgp base or frame 2 by means of. hollowprojections 3. The hollow projections 3 serve as tuyres anda branched blast pipe V4 leads from a blower 5 or any .other convenient source for producing an air blast through the branches 6 tothe hollow projections' ortuyres 3. The pipei is provided with a valve for regulatingthe blast and agauge 8 for have an opening -9 with a removable'plug l0 therein so that natural draft through theJ tuyres 3vmay be substituted when the blower 5 is shut off and the plugs 10 are removed.

The cupola 1 has its bottom 11 lined with refractory material such as fire brick, sand or la is rlined with fire re- Sistine material 12 vtguitable for nonfferrous metals. A housing 13 surrounds the upper end of the cupola 1 and leads to a stack 14 to which it is connected by means of the slip joint 15 so that the housingcan be raised Whenever repairs to the cupola .are required or the same is to be relined. zThe housing 13 `is provided witha door 16th-rough which the materials can be charged into the cupola. The housing 13 .is 'also provided with' countereights 17 to facilitate raising the same. A

p hole 18v and spout 19 are provided 'near the bottom of the'cupola anda slag liolgQO and a SPOut 21 are Drovidedat 'a-`so`xne\vl1at higher elevation.

My improved process of melting and relining non-ferrous metalsmay be carried out in such a furnace as follows: A thin layer of coke that is mechanically' strong and substantially free from sulfur and ash and pliesphorus is placed in the bottom of the cupola and ignited and the cupola is gradually filled with thiscoke to a depth of about a foot or two above the tuyres. The'coke' may be ignited in any-convenient manner, preferably by means of a gasor blow torch, the tap hole 18 and the openings 9 being left open until the furnace is ready to be charged with metal. It is desirable to `have the bottom ofthe cupola as well as the tap hole hot in the refining of these non-ferrous metals. After the bottom ofthe cupola has become hot and the coke has become incandescent, the' metal is placed thereon and'alternate layersof coke and metal may becharged, the metalthus being indirect Contact orassociation with thecoke when vand as the coke burns and becomes incandescent. The openings 9 are then closed by pluggmg, forexample, with a hard ball of cotton Waste, preferably oily or greasy, Y and moist molding sand. Theblast from the source 5 is then turned on `and enters the furnace through the tuyres 3. The pressure and amount of air through thetuyres is much less than is customary with cupola'furnaces for melting iron. It appears to be only necessary to supply sufficient airto support combustion: of-'the coke 1neta1,'so that instead sure atthe tuyres as is customary Withan iron melting cupola furnace of about 18 in` Without oxidizing the ,C 'i of having 7 ozs. of presdiameter at thebottom and 7\ft.f 6 in. yin

height, an air`A pressure of 2 toll ozs. is enough to carryoutmy process. AIt has been -found that it requires about three minutesof run-- ning wlth the' blast to melt bronzes, or four or live minutes to'm'elt copper. In some instances it has been found that the metal can be melted with the draught produced by the stack 14 with the plugs 10 removed Without using a forced draught fromithe source 5. When the metal is melted the tap hole 18 can be opened and the molten metal Withdrawn; by continually charging coke and rmetal through thedoor 16 the process can Vbe niade continuous, the molten metal in such` a case flowing out through the tap hole 18.` v If fluxing is necessary because of the-nature of the material beinvtreated, the slag can bedrawn oil' at intervals throuofh the slag hole 20. f-

It has been found at by using the cokezas above described in a cupola furnace for meltling non-ferrous metals, the metal, when drawn out of the taphole 18 is in a refined state and is of high quality and does n'otre- Y quire 4a subsequent .reliningoperatiom My improved process of melting and refining non-ferrous metals as above described has been found to result in a lower fuel consumption than is necessary with either a crucible or reverberatory furnace; the melting and refining can be accomplished in a` shorter period of time than with other types of furnaces; the` gases escape up the stack instead ofescaping into the plant as is often the case in non-ferrous foundries and smelting Works; the coke to be used by this process canV be obtained of substantially uniform quality thus eliminating uncertainties in the results; the shape and size of the metal to be melted is immaterial. The low blast enables fine material such as borings and turnings or other similar fine materia-ls to be melted, while the large sizes are/limited lonly 'by the lsize of the charging door; and a vciy small amount of slag is i'oduced from ash in the fuel as there is su stantially no ash in the coke. y i

By the term non-ferrous metal as used in the specification and claims is meantthose metals other thanv ferrous metals that canbe practically melted in a cupola furnace .and this term is intended `to. include the metals, copper, nickel, aluminum, tin, antiinony, leadand zinc and alloys theiseof, but exclude easily oxidizable metals such as magnesiumand alkali and alkaline earth metals.

By the term copper metals as used in the uclaims is meant copper, bronze and other alloys' of copper.

I claim:

1. The process which comprises melting a non-ferrous metal by burning .pitch 'coke which is substantially freefrom ash and niaterials that would have a deleterious effect upon said metal in direct'contact with said metal.

2..'l`he process which comprises melting a non-ferrous metal by burning pitch coke which is substantially free from the arsh and materials that would have a deleterious effect upon said metal and which possesses `rhigh compressive strength in direct contact with said metal.

l 8. The process which comprises melting a non-ferrous metal by burning coke which is substantially fre from ash and materials that would have ifgilgleterious effect upon said metal and whichcontains at least 98170 of fixed carbon in direct contact with said metal,

4. The process which comprises melting a non-ferrous metal by burning pitch coke which is substantiallyfree from ash and niaterials that would have a deleterious effect upon saidp'metal and which has a thermal value of about 14,50() B. t. u. perpound in direct contact with said metal.

5. rlhe process ,which comprises melting a anon-ferrous metal while in direct contact withincandescent pitch coke which is substantially free from ash and materia-ls that would' have a deleterious effect upon said metal, air being admitted to said incandescent coke and metal. during the melting of said metal in quantity sufficient to prevent an excessive oxidizing atmosphere.

osi

6. The process which comprisesnieltiiig a non-ferrous metal while supported by pitch collie which is substantially free from ash 'and materials that would have a deleterious effect upon said metal by burning said coke in a cupola furnace 1n contact with said metal.

7. The process which comprises melting a non-ferrous metal in a cupola furnace by burning pitch coke Wh ich is substantially free from ash and materials that would have a deleterious effect upon said metal in contact with said metal, the air blast through said coke during the melting of said metal being maintained below the pressures maintained in cupola furnaces for melting ferrous metals. l 8. The process which comprises refining impure copper by melting it by burning pitch coke which issubstantially free from ash and materials that would have a deleterious effect iiponsaid copper", and which possesses high compressive strength in contact with said copper.

9. The process Which comprises melting impure copper while in direct contact with incandescent pitch coke which is substantially free from ash and materials that would have `a deleterious effect upon said copper, air be.- ing admitted to said incandescent coke and metal during the melting thereof in quantity suflicient to provide areducing atmosphere.

10. The process which comprises melting aV non-ferrous metal ina cupola furace by burning in association therewith, pitch coke 4made in a bechive oven and' which is substantially free from ash and materials that would have a deletcriousei'ect upon said metal.

11. The process which Vcomprises melting ico copper iiietals'wliile supported by pitch coke which is substantially free from ash and materials that would have a deleterious effect upon said metals by burning said coke infcontact with sa'id metals.. y

l 12. The process which comprises melting copper' in a cupola furnace by burning in association therewith, at a teiiiperaturein ex` cess of the melting point of copper, pitch lcoke madein a beeliive oven and which is substantially'free from asTi and materials that would have a deleterious effect -upon the copper.

13. rl`he process which comprises'melting a non-ferrous metal in a cupola furnace' by burning in association therewitlnat' a temperature in excessV of the melting point of the `metal, pitch coke which is substantially free from ash and materials that would have a deleterious effect upon said metal and which possesses high compressive strength.

14. The process which comprises melting a non-ferrous metal in a cupola. furnace by burning in contact therewith pitch coke made in a beehive oven and which contains at least 98% of fixed carbon and has a thermal value of about 14,500 B.l t. u.:per pound.

15. The process which comprises melting copper metals in a cupola furnace by burning in contact therewith pitch coke made in a beehive oven and which contains at least 98% of fixed carbon and has a thermal value 10 of about 14,500 B. t. u. per pound.

16. The process Which'comprises melting copper metals by burning pitch coke which is substantially free .from 'ash and materials that Would have a deleterious elect u'pon said 15 4'DANIEL CUSHING.

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