US2177654A - Roasting and smelting furnace - Google Patents

Description

Oct. 371, 1939. w JAEGER 2,177,654

ROASTING- AND SMELTING FURNACE Filed March l5, 1937 5 Sheets-Sheet l 7 57 56 2e 55 26+ bff 2e -68`\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ l /l -.67 4# fw 26 'g- 53 22 2.5 9 621 1 2o 2 26 .20 2/ 23 /////////%9 f m4 y '7 f5 f8.. w/- mi Jian.: M//zr/Evgyef ,6 l ATTORNES Oct. 31, 1939. Hi w. JAEGER 2,177,654

ROASTING AND SMELTING FURNACE Filed March 15, 1937 s sheets-sheet s ATTORNEY Patented Oct. 31, 1939 PATENT OFFICE ROASTING AND SMELTING FURNACE Hans William Jaeger,

of one-half to Fred B.

Application March 15,

3 Claims.

This invention relates to roasting and smelting .furnaces of the reverberatory type and the primary object of this invention is to provide a furnace of this nature in which the roasting and smelting of ores is carried out in one continuous process.

Another object of the invention is to provi-de a continuous process roasting and smelting furnace of this type which is adapted to be constructed in comparatively small sizes thus making said furnaces available for use in smaller mining operations and making it especially desirable for use in mines which have poor transportation facilities and which are located at great distances from smelters,

j Another object of the invention is to provide a continuous process roasting and smelting furnace having three separately constructed sections providing an upper roasting chamber, a lower smelting chamber and a temperature control chamber positioned between the roasting and smelting chambers.

Another object of the invention is to provide a continuous process reverberatory roasting and v25 smelting furnace which is adapted for either low grade or complex ores, which is simple in construction and eiiicient in operation and which makes possible a substantial saving in transportation and smelter costs.

Another object of this invention is to provide a combined roasting and smelting furnace of this nature having means which collects and retains substantially all dust and substantially al1 zinc and arsenic and like substances which are 35 yvolatilized during the smelting process and which would otherwise pass out through the stack.

Another object is to provide a continuous process roasting and smelting furnace which uses less flux than is ordinarily used in the smelting of ores and which does not require any flux at all in the smelting of some ores.

Other objects are to provide a continuous process roasting and smelting furnace which saves in fuel due to the fact that it employs a hydrocarbon burner, which saves in the time of roasting and smelting, as the furnace can be tapped at more frequent intervals than the ordinary smelter furnace, which saves in the cost of labor required in connection with the roasting and smelting of ore and which obtains a higher percentage of recovery from the ores due to the maintaining of a more complete and even fluidity which results in a cleaner and more complete separation.

Other and more specific objects of the invention will be apparent from the following description taken in connection with the accompanying drawings.

In the drawings Fig. 1 is a longitudinal vertical section of a continuous process ore roaster Seattle, Wash., assignor Dawley, Seattle, Wash.

1937, Serial No. 130,811

(Cl. 26S- 10) and smelter constructed in accordance with this invention.

Fig. 2 is a transverse vertical section of the same, taken substantially on a broken line 2-2 of Fig. 1.

Fig. 3 is a horizontal section substantially on broken line 3-3 of Fig. 1.

Fig. 4 is a diagrammatic view of one form of driving means that may be used with the invention.

Like reference numerals designate like parts throughout the several views.

The continuous process roasting and smelting furnace shown in the drawings is made up of a lower ore smelting section I0, a medial temperature adjusting section I I, and an upper ore roasting section I2. The lower section IU comprises a smelting chamber I3 surrounded by walls I4 of heat resistant material, as iirebrick, and having a floor portion I5 preferably of silica sand. The entire structure may rest on a base I6 of concrete. Suitable openings I1 and I8 may be provided in the walls I4 of the lower section for tapping the same to draw off the slag and matte.

A hydrocarbon burner I9 extends into one end or into any other suitable portion of the smelting chamber I3 above the level which material will normally be maintained therein. The top of the smelting chamber I3 is formed by arches 2D of heat resistant masonry. These arches 20 have upwardly protruding portions 2I which intert telescopically with downwardly protruding portions 22 of the medial section II and form expansion joints between these two furnace sections. An upright passageway 23 connects the end portion of the smelting chamber remote from the hydrocarbon burner with a horizontal temperature adjusting chamber or passageway 24 in the medial section II. An inclined ore inlet passageway 25 communicatively connects the smelting chamber I3 with the medial section I I near the end at which the hydrocarbon burner I9 is positioned. The incline-d passageway 25 allows roasted ore to pass from the upper chambers into the smelting chamber I3.

The medial temperature adjusting section II and upper smelting section I2 are each supported on transverse metal beams 26 and said beams 26 are supported by a steel frame work 21 provided on the exterior of the roasting and smelting furnace. This means of support makes it possible to construct the three sections IIJ, II and I2 independently of each other and to provide successful expansion joints therebetween.

A roasting chamber 28 is provided in the upper furnace section I2 and an endless driven ore conveyor is provided in said roasting chamber. This endless driven ore conveyor comprises a plurality of links 29 operable on sprocket wheels 30. The sprocket wheels 38 are mounted on transverse shafts 3i and 32 which are journaled in bearings 33 positioned in the walls or external to the walls of the upper furnace section I2. Preferably both of the shafts Si and 32 are driven as by link belts 34 operating on sprocket wheel means 35 on said shafts and connected with sprocket pinion means 36 of transmission 3l. The sprocket pinion means 36 is connected by worm wheel 38, worm 39, bevel gears 40, sprocket wheel 4|, link belt 42 with a driving means as a motor 43 which preferably provides at least three different driving speeds. The above describe-d driving means provides for driving the ore conveyor at very slow speed and for applying the driving power at both ends of the same.

When necessary, especially in connection with relatively long conveyors, driving force may be applied at one or more locations between the two ends.

The links 29 of the conveyor are preferably in the form of specially constructed flat plates articulated together and extending substantially across the roasting chamber to form an endless traveling apron on which the ore may rest during the roasting process. These plate like link members 29 preferably rest upon track members 45 on the walls of the furnace as shown in Fig. 2. Preferably the shafts 3l and 32 are hollow, as shown.

An ore hopper it is positioned to deliver ore onto one end of the ore conveyor. A driven rotary feed valve 4l may be provided in connection with the hopper 46 to insure an even feed of ore onto theore conveyor and to prevent the escape of smoke and ley-products of combustion through the hopper.

A plurality of xedly mounted rabble arms 48 extend crosswise of the roasting chamber 23 above the ore conveyor and rabble blades 419 on said rabble arms extend downwardly into the path of the ore on the ore conveyor in suitable positions to stir and agitate the ore on the conveyor as it passes the location of said rabble arms. 'I'he rabble arms are of tubular construction providing for a circulation of air therethrough to keep said arms from becoming overheated.

The movement of the conveyor is timed so that the ore will be completely roasted as it is carried from the point of inlet to the discharge end of the conveyor. When the ore is discharged from the discharge end of the conveyor it falls through a vertical passageway 5@ onto an inclined metal plate or apron 5l which directs said roasted ore downwardly through the inclined passageway 25 into the smelting chamber i3. The apron 5E is of heat resistant material, preferably of cast iron and the major portion of the space beneath said apron 5l is open so as to afford a free circulation of air in contact with said apron for the purpose of cooling said apron. A wedge shaped deiector member 52 of metal is provided to protect the masonry from contact with the falling ores.

The medial furnace section I i is provided with a bottom portion 53, upright walls 54 and an arched top portion 55. An air space 56 is provided between the arched top po-rtion 55 of the medial furnace section and the bottom 51 of the upper furnace section. The upper furnace section has an arched top wall portion 58 above which is a flat top portion 59.

Positioned just in front of the ore inlet hopper 46 is a transverse passageway 69 for by-products of combustion; The walls enclosing the passageway SQ, preferably extend a short distance above the top of the furnace, Fig. 1, and said passageway communicates with one or more dust chambers 6l, Fig. 2, at one side of the furnace. The wall 62, Fig. l, between the passageway Gli and the hopper 46 extends downwardly to a location near the endless traveling ore conveyor leaving just enough clearance for the ore on the conveyor to pass under the bottom edge of said wall and forming a baffle plate helping to prevent hot gases, smoke and byproducts of combustion from passing outwardly through and around the hopper,

The dust chambers ti are each provided with a convergent lower portion 53 through which dust and solid by-products of combustion may pass downwardly to be disposed of in any suit-v able inanner while smoke and gases which can not be caught in these dust chambers pass outwardly and up through a stack til. To direct the heated lay-products of combustion downwardly in the dust chambers 6i and to assist in the removal, from the ley-products of the smelting and roasting furnace, of dust and gases which may carry values or which may be objectlonable if releasedin the atmosphere, I preferably provide in the top portion of each dust chamber a deflector wall which extends downwardly into the dust chamber. Also I provide means for spraying water into each dust chamber. This spray means may consist of water conduits @5 having perforations positioned to direct very nely divided sprays of water across the passageways l2 through which the by-products of combustion are traveling in a downward direction. Also I make the passageway 12, through which the ley-products travel downwardly, of smaller size than the passageways 'I3 r through which the ley-products travel upwardly. This accelerates the downward velocity of the by-products and helps to deposit the solid particles in the dust chamber. The water is sprayed under high pressure. This spray is very nely divided and thoroughly washes the gases which later escape upthe stack. Also the water spray helps to separate the solid matter from the gases by wetting the solid particles and causing them to adhere together so that they are more liable to drop into the bottom portions of the dust chambers. Any suitable drain means is provided in the bottom portions of the dust chambers to prevent the accumulation of water therein. This dust chamber and spray system forms an important partof this invention as it provides an ecient means for the recovery of values which mightl otherwise escape through the smoke stack and further provides means for cleaning the smoke and by-products of combustion of objectionable solid matter and gases. More than two dust chambers 6l may be provided if desired. i

I find that more heat than is required for the roasting of the ores will often be traveling upwardly through the passageways that lead from the smelting chamber i3 to the roasting chamber 23 and for the purpose of regulating this heat and utilizing said heat to the best advantage I provide in they end of the medial section Il two openings t6 and Eil. The opening 66 is connected with a conduit t8 which may lead to any suitable location where heat which is taken off may be utilized as for instance to boiler rooms. A damper 69 is provided in the conduit 63 and it will be understood that sufficient draft or suction is present in the conduit 68 to cause a portion of the heated gases to pass outwardly through this conduit 68 when the damper 69 is open or partly open. The opening 61 opens to the atmosphere and functions like a check draft for admitting cold air to the heated by-products of combustion, said opening 61 having a damper 10'by which it may be opened and closed.

In the operation of this continuous process roasting and smelting furnace, ore to be'roasted and smelted is fed from the hopper onto the ore conveyor and combustion is provided in the smelting chamber I3. As the ore is carried toward the discharge end of the conveyor the heated byproducts of combustion from the smelting chamber I3, which have traveled in a generally upward direction through passageways 23, 24 and 50, pass over said ore and roast it to the desired extent. The ore is spread out in a relatively thin layer on the ore conveyor and is stirred by the rabble blades as it progresses thus giving the heated gases even access to all of said ore and roasting the same thoroughly in a short period of time. The speed of the ore conveyor may be varied to vary the roasting time for different ores and in proportion to different degrees of heat. The thoroughly roasted ores discharge into the reverberatory smelting chamber Ai3 where they are reduced to a molten or uid state providing for a gravity separation of the gangues from the metals, thus permitting rst the slag and then the matte to be tapped off in the usual manner.

From the foregoing description it will be seen that I have provided a continuous process roasting and smelting furnace which can be constructed in small sizes at a cost which makes possible its installation at smaller mines; that fI have provided a continuous process roasting and smelting'furnace in which the ores pass directly from a roasting chamber into a smelting chamber and in which the excess heat from the smelting chamber is utilized for roasting the ores thus reducing heat losses and costs of ore handling to a minimum. Also by providing the temperature control chamber between the roasting and smelting chambers I have provided an efficient means for controlling the temperature in the roasting chamber. The dust chamber further provides a simple and efficient means for recovering values and removing objectionable gases which would otherwise escape through the stack.

The foregoing description and accompanying drawings clearly lshow a preferred embodiment of my invention but it will be understoodthat this disclosure is merely illustrative and that such changes may be made as are within the spirit and scope of the following claims.

I claim:

1. In a continuous process roasting and smelting furnace; a smelting chamber; a roasting chamber positioned directly above said smelting chamber; movable ore supporting means in said roastingchamber positioned to discharge roasted ore from one end portion of said roasting chamber downwardly into a corresponding end portion of said smelting chamber; and a temperature control chamber positioned between said smelting chamber and said roasting chamber and communicatively connected with the ore discharge end of said roasting chamber and the opposite end of said smelting chamber and providing a,

passageway through which heated products of combustion from said smelting chamber may pass to said roasting chamber; hot gas take off means connected with said temperature control chamber; and cold air inlet means connected with said temperature control chamber, said hot gas take ofi' means and cold air inlet means providing for the control of the temperature of the gases passing through said temperature control chamber to said roasting chamber.

2. In a continuous process roasting and smelting furnace, a smelting chamber; a hydrocarbon burner in said smelting chamber; a roasting chamber positioned directly above said smelting chamber; a temperature control chamber positioned between said roasting chamber and said smelting chamber communicatively connected at one end by a hot gas passageway with said roasting chamber and at the other end by a hot gas passageway with said smelting chamber providing conduit means through which hot gases may pass from said smelting chamber to said roasting chamber, said three chambers being substantially horizontal and said hot gas passageways extending in generally upright directions between said chambers; an endless traveling ore conveyor mounted in said roasting chamber positioned to discharge ore downwardly through the hot gas passageway which connects said roasting chamber and said temperature control chamber and across the path of the ascending hot gases; means forming a conduit between said temperature control chamber and said smelting chamber substantially at the bottom of the hot gas passageway connecting the roasting chamber with the temperature control chamber through which said ore may pass downwardly into said smelting chamber; temperature control means connected with said temperature control chamber providing for the control of the temperature of gases passing through said temperature control chamber to said roasting chamber; and means admitting ore into the intake end of said roasting chamber onto said traveling conveyor.

3. In a continuous process roasting and smelting furnace, a relatively long horizontal smelting chamber; heat generating means in said smelting chamber; a temperature control chamber positioned directly above said smelting chamber substantially parallel therewith; passageway means for heated gases connecting one end portion of said temperature control chamber with the adjacent end portion of said smelting chamber; an inclined deflector plate positioned at the other end portion of said temperature control chamber; passageway means for material positioned at the lower edge of said inclined plate communicating with said smelting chamber; a roasting chamber positioned directly above said temperature control chamber substantially parallel therewith; passageway means communicatively connecting the end portion of said temperature control chamber adjacent said inclined plate with the adjacent end portion of said roasting chamber; ore inlet means positioned at the other end portion of said roasting chamber; ore moving means in said roasting chamber adapted to move ore from said ore inlet through said roasting chamber and discharge the ore onto said inclined plate; and temperature control means connected with said temperature control chamber.

HANSV WILLIAM JAEGER.

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