US2330487A - Smelting apparatus - Google Patents

Description

J. H. GRACE SMELTING APPARATUS Sept. 28, 1943.

Filed April 2, 1942 2 Sheets-Sheet 1 INVENTDR JOHN HEDLEY GRADE EIYfm ATTCJRNEY Sept. 28, 1943. J. H. GRACE SMELTING APPARATUS Filed April 2, 1942 2 Sheets-Sheet 2 INVENTDR JEN-IN HEDLEY GRACE ATTORNEY Patented Sept. 28,1943

"( ame SMELTI PARATUS v John Hedley Grace, Vancouver, Britishfiolumhia;

Canada, v assignor tov Ronald etna; l

col ve Bri ish Co u a, Camila "Applicationyilpril 2, 1942,Seriall\*o. 437,441

2 Claims;

This invention relates toimprovements in furvnaces for smelting ores" and particularly iron ores.

vision of a furnace for smelting ores and particularly iron ores; inplaces where coking coalis not readily available and is,'therefore,so expensive that it makes the cost of smelting prohibitive. Another object is the provision. of a smelting furnace for ores in which non-coking coalg such An object of thepresent invention is the proas low grade bituminous or lignite'coal, or'fpetror- .leuin oil or other cheap carboniferous material,

may be used. Y 1 v e A further object is the provision of a smelting furnace for ores bymean'sIof which the cost of producing iron and other metals, and particularly steel, is considerably reduced;-

A further object is the DIOVlSlOllOf a smelting furnace for iron ore in Which'thes'ame heat is used for reducing "the core, and refining and alloying the iron to any desired steel product.

Another object has been to design a'sm elting furnace whereby liquid,- gaseous, or powdered fuels may he used in combination with electrical energy, thereby conserving to a great extent the consumption of electrical current and thus effect.- ing a great economy in operation.

Still another object has been to design a smelt ing furnace wherein heat losses are reduced to the minimum while charging and alloying, and oifering greater facility of operationthan usual in furnaces of this kind. s a

With the above and other objects'in View, the

present invention consists of smelting apparatus comprising a horizontally-inclined rotatable kiln,

means for rotating the kiln, means for supplying charged ore to the kiln at the upper end thereof, means for directing hot reducing gases through the kiln, and an electric furnace connected to the lower discharge end of the kiln,said furnace receiving the reduced materials from the kiln for refining, as more fully described in theyfollow ing specification and illustrated in the accompanying drawings, in which i 'J p e Figure 1 is aside elevatiompartly in section,

- of the smelting apparatus,

Figure 2 is a sectionaljyiew taken on the line 22 of Figure 1, .Y

Figure 3 is a reduced elevation of theapparatug i p p Referring more particularly to" the drawings,

i0 is a horizontally-inclined, openended kiln rotatably mounted in any suitable manner, such as by means of bearings carriedbya platform l2 mounted on legs l3.

' I he kiln is rotated in o t so s e f te i v Q11? nd spaced from! th .m of heaters 'with'a valve 39 An electric in;

an es re sewnaecqrwsc i s a it; i h m shes W h l r n se '6 moun den i n; ki a a mar m nu-lad v. A new: it is? eq eteslaq e swhe ip??? 9? eed iend rine Kiln eas ea pe at ends o wardl f m t e hermit end exfi int? t empire Pes r e s and' crut; p ts. 5 fiwell qwni en rus s f; i

e meating 1 ture with the sha 25 'vided for formin 9 th ir s iq lieha for ama s a lsh tyraherfns 1 i an fixfifilti m nected to the lower end r ac n? xam a tn hre .1 a six standardized 32 the f rnace; a -tight Wat o th tenn be conne ted .0 an Q51 in li er? trol these valves in accordance with the temperature of the gases at the outlet of the chamber.

The kiln l0, shaft 25, electric furnace 3|, and combustion chamber 31 are lined with a suitable refractory material.

A pipe M having a gas pump 45 therein extends from the dust catcher 2| to a point adjacent the pyrometer 42 where it terminates in a nozzle 46.

The operation of this apparatus is as follows:

Oil from the pipe 40 is mixed with a limited supply of air from the pipe Al and burned in the combustion chamber 37 which is so shaped thatthe products of combustion or gases are thoroughly mixed before passing through the restricted opening 33 into the kiln lb. The Whole apparatus is kept air-tight and the limitation of the quanttiy of air supplied to the combustion the hopper through the feed pipe into the kiln 10 which is slowly rotating. As the kiln rotates it automatically removes a certain proportion of the charge from the hopper and the charged ore progresses slowly along the inclined kiln towards the shaft 25. During the earlier part of the progress of the charge along the kiln the (volatile constituents of the charge are driven off and the coal forming the reducing agent is carbonized at a low temperature. As the charge moves, it is subjected to a continuous increase in temperature, derived from the hot reducing gases from the combustion chamber, which pass in the opposite direction to the progress of the charge. The duration of the charge in the kiln must be sufliciently long to. allow full reduction of the iron oxide to metallic iron. Crushing of all materials to small particles permits of rapid heat penetration and chemical reaction.

The design of the combustion chamber 3'! assures a thorough mixing of the gases therein and permits a reducing atmosphere being maintained throughout the kiln and prevents any free oxygen entering therein and reoxidizing the already reduced ore. The thermostat 63, owing to its control of the supply of oil and air to the combustion chamber, automatically regulates the constituents of combustion in the chamber, thereby controlling the temperature in the kiln and keeping it at a predetermined temperature, so as to assure the most rapid reduction and chemical reaction in the pre-heating and reducing zones, while avoiding the overheating of the charged ore in the kiln, which would cause it to become plastic and stick to the wall of the kiln and block the passageway thereof.

The sponge iron, with the other materials of the charge in a loose, disintegrated condition, and retaining its heat, is discharged from the kiln directly and continuously into the shaft and falls directlyinto the electric furnace 3i. It retains the loose, separate character of its particles during its fall down the shaft. The charge in this condition and at an approximate temperature of 1000 degrees Centigrade is then subjected to the heat from the electric are, where it is melted. When sumcient metal has collected, the slag is run all through the slag hole 35. The molten iron may be refined, and and slag made basic or acid as desired to remove any objectionable elements in the iron, by charging the necessary material through the hopper 28 at the top of the shaft. When the molten iron is suffiicently' refined, any desired grade of pig iron may be made by charging through the hopper 28 the necessary alloy.

If desired, the refining and alloying may be done in separate electrical furnaces so as not to interfere with the continuous action of the apparatus.

During the period of refining and alloying, the rotating kiln and the exhaust fan 23 are stopped, the gases from the electric furnace escaping through the hopper at the top of the shaft.

large volume are rich in carbon monoxide, owing to the' fact that the oil in the combustion chamher is not fully combusted and the excess carbon in the charge maintains a reducing atmosphere they may be stored and'used for any desired pur-- pose.

Some of the gases are pumped from the dust. catchers through the pipe 44 by the pump 55 to the nozzle 46 where they are burned continu-- ously. The flame at the nozzle acts as a gauge to indicate the condition of the gas passing. through the kiln. Carbon monoxide is necessaryfor the proper chemical action in the kiln and.

if too much air is admitted to the combustion chamber 37 or if any air gets intothe apparatus, the gas is converted to carbon dioxide in the kiln which will re-oxidize the iron. If carbon monoxide passes through the pipe 44, the flame is high but if carbon dioxide reaches the nozzle 4-5, the flame is low and spluttering, thus indicating the character of the gas in the kiln.

Ihis apparatus permits the use of petroleum oil, both as a reducing and heating agent, for the preheating of the charge and the reducing of the iron ore while in the rotating kiln, or non-coking coal may be used both as heating and reducing agent for the charge in the kiln; but it is to be understood that in the electric furnace 3i the sole'heating agent is electric energy only.

The large volume of gases that pass through the rotating kiln are rich in carbon monoxide, and may be used under steam boilers or for other commercial purposes.

By fully reducing the iron ore and preheating the charge in the kiln, by a separate and coinparatively cheap heating agent, such as powdered coal or fuel oil, a great economy is gained, in saving a large amount of electric energy that otherwise would be necessary for the melting of the charge in the furnace.

Various modifications may be made in this invention without departing from the spirit thereof or the scope of the claims, and therefore. the exact form shown is to be taken as illustrative only and not in a limiting sense, and it is desired that only such limitations shall be placed thereon as are disclosed in the prior art or are set forth in the accompanying claims.

What I claim as my invention is:

l. smelting apparatus comprising a horizontally-inclined rotatable kiln, means for supplying charged ore to the upper end of the kiln, a charging shaft at the lower end of the kiln, said kiln The. gases which pass through the rotating kiln in.

opening into the shaft adjacent the top thereof, a combustion and mixing chamber having a restricted opening which communicates with the shaft, means for supplying fuel to the chamber,

means for supplying a limited amount of air to v the chamber, the incomplete combustion of the fuel in the chamber producing a reducing atmosphere for the kiln, an electric furnace connected to the lower end of the shaft to receivethe re-,

I the kiln, means for supplying charged ore to the upper end of the kiln, a vertical charging shaft at the lower end of the kiln, said kilnopening into the shaft adjacent the top thereof, a combustion and mixing chamber gradually narrowing down to a restricted opening which communicates with the shaft opposite the lower end of the kiln, means for supplying fuel to the chamber, means for supplying a limited amount of air to the chamber, means for controlling the fuel and air supply to the chamber, the incomplete combustion of the fuel in the chamber producing a reducing atmosphere for the kiln, an electric furnace connected to the lower end of the shaft to receive the reduced ore from the kiln, said reducedfore being melted in the furnace, and an exhaust fanlconnected to the upper end of the kiln adapted to draw heat from the ,furnace and the reducing atmosphere through the kiln.

JOHN HEDLEY GRACE.

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