US2311648A - Mercuric ore reduction furnace - Google Patents

Description

Feb. 23, 1943. F, DUNCAN 2,311,648

MERCURIC ORE REDUCTION FURNACE Filed Sept. 11, 1941 3 Sheets-Sheet l I' 40 AZ gin/0mm Zinnia Duncan? Feb. 23, 1943. UN N 2,311,648

MERGURIC ORE REDUCTION FURNACE 3 Sheets-Sheet 2 Filed Sept, 11, 1941 Fra n7: pu77aan fame/mm Feb. 23, 1943. P DUNC N 2,311,648

MERCURIC ORE REDUCTION FURNACE Filed Sept. 11, 1941 3 Sheets-Sheet 3 Patented Feb. 23, 1943 UNITED STATES PATENT QFFHCE MERCURIC ORE REDUCTION FURNACE Frank Duncan, Terlingua, Tex. Application September 11, 1941, Serial No. 410,455

7 Claims.

This invention relates to a furnace of novel and simple construction through which finely crushed sulphide ores, such as Cinnabar, are adapted to flow by gravity, having means for roasting the ore, and means for removing the mercuric fumes, released from the ore by the roasting thereof, from the ore, and for conveying the fumes through the furnace and to an exit passage leading to a condenser.

More particularly, it is an aim of the invention to provide an ore reduction furnace of very simple construction having only one moving part. which part functions for conveying the roasted ore, after the removal of the mercuric fumes therefrom, from the furnace, and also for controlling the rate of flow of the ore through the furnace.

Another aim of the invention is to provide a throat through which the ore passes having superposed baffles over which the ore must flow and which causes the ore to flow, at certain points, in very fine streams so that the ore can be readily heated and subjected to heated air, passing back and forth through the throat, for extracting mercuric fumes from the ore.

Still a further aim of the invention is to provide a furnace having heating means for heating the throat and the ore passing therethrough, and which heating means is separated from the ore by the throat so bustion from the heating means do not come in contact with the ore to thereby prevent the mercuric fumes from the ore, which are conveyed by heated air to a condenser, from being mixed with carbon monoxide gases from the products of combustion.

A particular advantage of the invention resides in the fact that in spite of the fact that the finely crushed ore is thoroughly dried previous to being admitted into the furnace, the ore will contain a certain amount of moisture that can only be eliminated by heat and which is eliminated by the heating of the ore passing downwardly through the furnace to produce steam which is mixed with the hot ascending air and which has a tendency to prevent the mercuric fumes from condensing on the cooler ore, near the top of the furnace.

Other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, which illustrate preferred embodiments of the invention, and wherein:

Figure 1 is a longitudinal vertical sectional that the products of com- Walls 19 of the bore I2.

view of a furnace constructed in accordance with the invention,

Figure 2 is an enlarged fragmentary longitudinal vertical sectional view of the same, taken substantially along the plane indicated by the line 2-2 of Figure 1.

Figure 3 is an enlarged fragmentary vertical sectional view of a portion of the furnace taken substantially along a plane indicated by the line 33 of Figure 2,

Figure 4 is an enlarged cross sectional View of the furnace taken substantially along a plane indicated by the line 4-4 of Figure 2,

Figure 5 is a View similar to Figure 4, showing a slightly modified form of the furnace,

Figure 6 is a fragmentary vertical sectional view of a portion of the furnace, taken substantially along a plane indicated by the line 66 of Figure 1, and

Figure 7 is a cross sectional View of the furnace taken substantially along a plane indicated by the line 1-7 of Figure 2.

Referring more particularly to the drawings, wherein like reference characters designate like or corresponding parts throughout the different views, it) designates generally a furnace casing formed of a refractory material, such as brick. The furnace casing i0 is elongated, as seen in Figure 1, and is disposed in substantially an upright position and is substantially rectangular in cross section, as seen in Figures 4 and 7, to provide a substantially stack-shaped casing, the lower end H of which is enlarged. The furnace casing I0 is provided with a bore l 2 in the upper part thereof which extends from the top of the casing l0 into its enlarged bottom portion Ii, and the Width of which is restricted above the point 13, as seen in Figure 1, for a purpose which will hereinafter become apparent.

A throat, preferably of metal, designated [4, extends longitudinally through the bore t2 from near its upper end to a point near its lower end. As seen in Figure 2, the bore l2, above the upper end of the throat M is tapered to form a bin l5 adapted to receive finely ground ore, not shown.

The throat M, as best seen in Figure 4, is ovalshaped in cross section and the bore i2 is elongated and rectangular in cross section and is provided with longitudinally extending recesses l 6 in the edge portions thereof in which the arcuately shaped ends ll of the throat M fit. The sides I8 of the throat M are spaced from the side The throat I4 is provided with longitudinally extending walls 20, near its edge portions l1 which divide the throat, lonparent that the lower gitudinally, into an intermediate chamber 2| and corresponding chambers 22, which chambers 22 are formed by the arcuately shaped edge portions I1 and the walls 20, which are adjacent thereto. As best seen in Figure 2, the bin I opens into the upper end of the intermediate chamber 2I.

As best seen in Figure 3, the chamber 2I contains a plurality of superposed baffles 23 which are preferably in the shape of an inverted V, in cross section, and each of which is attached at its ends to the walls 20. The upper edge of each baille 23 is disposed substantially at the same level as the bottom edges of the sides of the baffle 23 thereabove and said bottom edges of the sides of the baflles 23 are spaced from the side walls I8 of the throat I4 to form relatively narrow slots or openings 24 therebetween. As seen in Figures 1 and 3, the walls are provided with the correspondingly disposed openings 25 which open into the cavities 26 formed by the baffles 23 which cavities, combine with the openings 25, which communicate therewith, to form passages between the chambers 22.

As best seen in Figure 2, the chambers 22 are provided with dividing walls 21 which are disposed transversely thereof. One of the chambers 22 is provided with two walls 21, disposed near the ends thereof, and the other chamber 22 is provided with an intermediate wall 21 so that said walls 21 are staggered, for a purpose which will hereinafter become apparent.

The bore I2 is provided with a transverse dividing wall 28 on which the lower end of the throat I3 rests, and which is provided with an elongated opening 29 which communicates with the chamber 2I, as seen in Figures 1 and 3, and a restricted opening 30, at one end thereof, which communicates with the lower end of the chamber 22, which contains the two dividing walls 21, as seen in Figure 2.

At substantially the same elevation as the wall 28, the furnace casing I0 is provided with supporting shelves 3I which project outwardly from the opposite sides 32 thereof and through which extend burners 33 of any suitable construction. Above the shelves 3I, the sides 32 of the casing III are provided with opposed openings 34, as best seen in Figures 1 and 3, which diverge inwardly and which open into the spaces formed by the sides I8 and IS. The burners 33 discharge into the openings 34 and it will thus be readily apportions of the chambers 35 will form fire boxes for receiving the flames, as indicated at 36, from directed inwardly through the openings 34 to impinge against the sides I8 of the throat I4 for heating said throat. The upper portions of the spaces 35 form fiues and are provided, at their upper ends, with outlet openings 31, as seen in Figure 1, through which the products of combustion can be released from the furnace casing I9 without coming in contact with the interior of the throat I4.

Below the wall 28, the bore I2 is provided with a plurality of pairs of bafiles 38. The bafiles 38 of each of the pairs thereof are attached to complementary portions of the sides I9 of the lower part of the bore I2 and converge downwardly and inwardly relatively to one another and terminate with their lower, adjacent edges in spaced relationship to one another to form slotted passages 39 therebetween. Each of the pairs of baffies 38 combine to form a hopper, designated generally 49, with the slotted passages 39 forming the outlets thereof, and said hoppers are arranged one the burners 33 which are I 5I and is discharged outwardly of the above another and beneath the opening 29 of the plate 28.

The lower portion II of the casing I0 is provided with an enlarged hollow interior having an inclined bottom wall 4I, said interior forming a container 42 into which the lower end of the bore I2 opens. A hot air heater 43, of any suitable construction is disposed in a portion of the container 42 and is provided, adjacent its bottom, with anair intake pipe 44 which extends from the container 43 outwardly through the casing portion II and which is provided, on the outer side of the casing portion II, with a control valve or damper 45 for limiting the amount of air passing through the pipe 44 and into the heater 43. The upper end of the heater 43 extends into the lower end of the bore I2, adjacent one side I9 thereof and is provided at its upper end with pipes 45 and 41 which project therefrom in opposite directions and toward the narrow side Walls 48 of the casing I0, one of said pipes being'disposed, at its outer end, adjacent each of the sides I9 of the bore I2. The walls 48 are each provided with two sets of passages, 49 and 50, which connect with the pipes 46 and 41, respectively. All of the passages 49 and 50 have inturned ends which open into the bore I2 and said passages 49 and said passages 50 are staggeredly arranged, as seen in Figures 2 and 6, in the walls 48. The lower end of the lowermost passage 49 is connected to the outlet end of the pipe 46 and the lowermost end of the lower passage 59 is similarly connected to the pipe 41. The remaining ends of the passages 49 and 50, as seen in Figures 1 and 3, open into the bore I2, adjacent the sides I9 thereof and on the outer sides of the baflles 38, and the upper ends of the uppermost passages 49 and 50 open into the bore I2, between the upper hopper 40 and the wall 28. As indicated by the arrows 5| (Figure 6) the hot air from the heater 43 passes through the pipe 46 and the passages 49 and therebetween and on the outer sides of the baflies 38 back and forth through the bore I2 and into the space between the wall 28 and the upper hopper 40. As indicated by the arrows 52, seen in dotted lines in Figure 6, hot air from the heater 43 also passes from the pipe 41 through the passages 58 back and forth through the bore I2 and on the outer sides of the bafiies 38, which are disposed adjacent the side I9, opposite to the side adjacent to which the heated air, indicated by the arrows 5|, passes. The heated air from the pipe 41, as indicated by the arrows 52, flows in the opposite direction to the heated air indicated by the arrows from the upper end ofthe uppermost passage 50 into the space between the wall 28 and the upper hopper40, where the air from the passages 49 and 50 intermingle and flow into the chamber 22, containing the two dividing walls 21, through the opening 30. V

A passage 53 communicates with the restricted bottom of the container 43 and is adapted to have one end, not shown, opening outwardly of the bottom portion II of the casing. Passage 53 contains a driven screw conveyor 54, which forms the only moving part of the furnace, and which is adapted to convey the ore, after roasting, away from the furnace. The upper end of the chamber 22, which is provided with the two dividing walls 21, is provided with a pipe leading therefrom furnace casing I0 and which pipe 55 is adapted to be connected to a conventional condenser or condensers, not shown.

The bin I5 is adapted to be filled in any conventional manner with finely crushedsulphide 'ore, the largest particles of which are preferably less than one-half inch in length between the two most remote points thereof. This finely crushed ore, not shown, flows downwardly from the bin l into the chamber 2| and successively over the bailles 23. The ore is discharged from the throat l4 through the openings and passes successively through the hoppers into the container 42 from where the ore is conveyed outwardly through passage 54. The parts previously mentioned will be substantially filled with the ore so that the flow of ore through the furnace is governed by the speed at which the conveyor 54 is driven for conveying the ore from the container 42, and said conveyor is adapted to be driven at a speed to cause the ore to pass downwardly very slowly through the furnace. Consequently, the ore passing over each bafile 23 is divided and flows in two fine streams through the slots 24. slot 24 it spreads out at the enlarged part of the next bafiie therebeneath and in so doing a rolling action of the ore is produced thereby thoroughly mixing the ore a plurality of times while passing through the throat M.

The heated air after passing upwardly through opening 30 is directed by the lowermost dividing wall 27 from the chamber 22, into which it flows from the opening 383, through the passages, formed by the openings 25 and the cavities 26 to the other chamber 22'. The air is directed by its dividing wall 21 back into the other chamber 22 in a like manner and so forth until it reaches the upper end of the first mentioned chamber 22 from which it passes through the outlet pipe 55. The ore passing slowly over the baffles 23, as previously described, forms a seal around the passages through which the heated air passes from one to the other of the chambers 22. The heated air heats the ore to there by cause the mercuric fumes therein to be released into the air and said fumes are conveyed with the air out through the pipe to the condensers. The rolling action of the ore, pre viously described, causes the heat from the air to more readily penetrate the ore. In spite of the fact that the ore is thoroughly dried before entering the throat !4 it will still contain a certain amount of moisture of saturation that can only be eliminated by heat and this moisture will be converted into steam by the heated air in the upper part of the throat I 4 and this steam tends to prevent the mercuric fumes from condensing on the cooler ore entering the upper end of the throat. The dried ore continues to flow downwardly to a point between the burners 33, which constitutes the greatest heat area and where the ore is sufficiently heated to vaporize all mercuric minerals, but not heated sufficiently to fuse or melt any other minerals or rock. The extent of the heat at this point, must necessarily be determined by the nature of the ore being treated.

The roasted ore after passing the lowest baffle 23 flows through opening 29 and into the upper hopper 46 and then successively through the hop pers 40 passing in line streams through their slotted passages 39. The hoppers 48 form scrubbing hoppers to scrub out any mercuric fumes that may be left in the roasted ore which fumes would be picked up by the air passing on the outer sides of the baflles 38. The hoppers 49 are also superheated by the roasted ore so that their baflies 38 increase the heat of the air passing therearound to superheat the air sufficiently 53 by the screw conveyor After the ore passes each ores that it may contact make use of waste heat from to reduce any mercuric and to thereby the roasted ore.

From the foregoing it will be readily apparent that the mercuric fumes are removed from the ore by the heated air and conveyed to the outlet pipe 55 without coming in contact with the gases contained in the products of combustion from the burners 33'. Consequently, the carbon monoxide gases of these products of combustion do not come into contact with the mercuric fumes as they are conveyed separately from the furnace through the fines 35 and the flues outlets 31, as previously described.

Obviously, the capacity of the furnace could be increased by providing a plurality of throats, as indicated at M in Figure 5, each of which would be of the same construction as the throat l4. If the furnace were provided with two throats i4, as seen in Figure 5, it would have to be widened so that the throats could be disposed in side by side relationship, and in order to heat the adjacent sides 48' of the throats [4, an additional pair of burners 33' mounted to discharge into openings 34a in the walls 48'. The openings 34a communicate with space 35a, between the adjacent walls 3?, and such space forms an additional fire box and flue, so that both sides I8 of both throats I4 will be heated, as the outer sides l8 will be heated in the usual way by burners 33' through openings 34 which communicate with the spaces 35 which form fire boxes and fiues similar to the spaces It will be readily apparent that separate hoppers 40 and heaters 43' could be provided for the two throats M or both throats could .discharge into a single set of hoppers 40 and a single heater 43 be used with the heated air from thereof being discharged into of the throats and the heated air from the other of said pipes being discharged into the other throat.

From the foregoing it will be apparent that the applicants furnace is designed for roasting only fine ores, dust, soot and condenser residue of other types of mercurlc furnaces, and by havwhich in turn is governed by the speed at which the conveyor 54 is driven.

Various modifications and changes are contem plated and may obviously be resorted to as only a preferred embodiment of the invention has been disclosed.

I claim as my invention:

1. An ore reduction furnace comprising an elongated, substantially upright furnace casing, a throat extending downwardly to a point adjacent the bottom thereof, a portion of said throat being adapted to form a passage for finely ground ore which is adapted to flow downwardly therethrough by gravity, inverted V-shaped baflle members disposed one above another in said throat and over both sides of which the ore is would be provided and adapted to flow, passages having portions formed throat being oval shaped in cross section and by said baille members adapted to convey heated being provided with wall portions extendinglonair by a circuitous route back and forth, through gitudinally thereof and disposed adjacent its said throat and in an upward direction exteriorly edges, and forming elongated, substantially per- 015 the portion of the throat through which the pendicular spaces in the edge portions of the ore passes, and heating means disposed in the throat, superposed arch shaped members arfurnace and on the outer side of said throat for ranged in the central portion of the throat and heating the ore and air passing therethrough, connected to said walls and forming baflles over said furnace comprising spaced superposed hopwhich the ore is adapted to flow in relatively thin pers arranged below said throat for receiving Streams, said walls being provided with opposed the ore therefrom and through which the ore openings connecting Said paces with the insuccessively passes, and means for conveying the teriors of said arch shaped s, said openheated air back and forth around the outer sides mas and the interiors of said arch shape of aid hoppers, bers forming passages between the spaces, and

2. A furnace comprising an elongated hollow 5 said spaces being provided with spaced stagshaft like furnace casing, a throat member exer dly arranged transverse walls adap to tending through a portion ther f and through form baflies whereby heated air will be directed which finely ground r i adapted t b circuitously back and forth through the arch veyed by gravity, means for restricting the disshaped members so that the mercuric fumes, eoncharge of the ore from the furnace for controlt in i th a p d up by e heated ling the flow of the ore through the throat, superair passi g therethrough, and means for admitposed baiile means disposed in the thr at a d ting the air at the lower end of said throat and over which the ore passes in its movement therefo re e s ng the a r from the furnace at the through, means for heating the outer side of said upper end of the throat. throat for heating the ore passing therethrough, 5. A furnace as in claim 4, the sides of said and means for conveying air circuitously back throat being spaced'from the walls of the furand forth through the baiiies for carrying off nace casing, heating means disposedinthe spaces gases released from the ore by the heating theres formed for heating the throat for heating of for separating the gases from the ore. the ore and air passing therethrough, and said 3. A furnace as in claim 2, said bailles each last mentioned spaces forming flues for carrying being of inverted V-shape in cross section and Off the P d Of Combustion from e heating being disposed in substantially the same vertical means.

plane, and said throat having substantially par- 6. A furnace as in claim 4, comprising a bin allel sides adjacent to which the lower edges of adapted to receive the ore from the lower end the baiiles are disposed to provide narrow pas- '35 0f the throat, and a pass ge leading from said sages through which the ore must pass. bin and provided with a driven conveyor for con- 4. Amercuric ore reduction furnace comprising veying the ore from the bin and for limiting an elongated, substantially perpendicularly disthereby the flow of ore through the throat.

posed furnace casing having a bore disposed to '7. A furnace as in claim 4, Comprising a hot air extend substantially from end to end there- 40 hea er d sposed in said furnace casing and bethrough, a throat member disposed longitudinally neath the lower end of said throat for initially of said bore and through which finely ground heating the air to be conveyed through the throat. mercuric ore is adapted to pass by gravity, said FRANK DUNCAN.

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