US2084830A - Metallurgical process and apparatus - Google Patents

Description

June 22, 1937. E. A. BARNARD ET AL METALLURGICAL PROCESS AND APPARATUS Filed July 31, 1955 4 Sheets-Sheet l E/vo CHA. fi/nP/vA/Po. BY [fa /7 (I'M GU/EE.

*LLLLLLLL /%/W%ATTORNEYS June 22, 1937. A, BARNARD ET AL 2,084,830

- METALLURGICAL PROC ES 5 AND APPARATUS Filed July 31, 1935 4 Sheets-Sheet 2 z ATTORNEYS June 22, 193 7.

E. A. BARNARD ET AL 2,084,830 METALLURGICAL PROCESS AND APPARATUS Filed July 31, 1935 4 SheetsSheet 3 Q 3 INVENTOR3 O N O ENOCHABAENA/w &\ I 6 BY HUGH JMGU/BE.

E. A. BARNARD ET AL METALLURGICAL PROCESS AND APPARATUS June 22, 193 7.

Filed July 31, 1935 4 Sheets-Sheet 4 1 ENTORS E/VOCHA.5ARNA/?D.

terial.

Patented June 22, 1937 UNITED STATES PATENT OFFICE METALLURGICAL PROCESS AND APPARATUS Enoch A. Barnard and HughJ. Maguire, Anaconda, Mont, assignors to Anaconda Copper Mining Company, New York, N. Y., a. corporation of Montana Application July 31, 1935, Serial No. 33,979

centrates or the like, or on metals or alloys,

The invention makes possible the use of furnaces of various types and dimensions and increases fuel efficiency and capacity by making a larger percentage of the furnace hearth available for smelting. The invention also increases the life of the furnace structure by keeping the flame gases of the highest temperature down upon the surface of the charge and the gases of a lower temperature in contact with the furnace roof and upper portions of the side walls. The flames are applied directly upon the surface of the charge.

The furnace may be of any desired shape, either circular, oval, oblong, rectangular or square depending upon the kind of operation desired. A sprimg arch or suspended arch may be used over the furnace depending upon the shape and size of the furnace or the preference of the designer. The furnace may be operated as a dry hearth furnace with the charge to be smelted resting in piles along the side walls or upon the hearth of the furnace. The furnace may also be operated as a bath furnace with the charge floating upon a molten bath of smelted material upon the fur- 3o nace hearth. The furnace may also be operated using a combination of these two mentioned methods.

Numerous small fuel burners are provided at points in the end, sides or roof or any combina- 40 fuel and gas sweeps over the unsmelted charge.

The'fuel ignites immediately upon leaving the burner nozzle and continues to burn in its passage over and in contact with the unsmelted ma- The force due to the velocity of the fuel and air stream keeps this stream down upon and in contact with the unsmelted charge. The fuel and air stream decreases in velocity upon approaching the center of the furnace and changes its direction to that ofthe waste gases which are passing to the furnace gas oiftake. This-change of direction gives the fuel and air a further mixing and completes the combustion in close proximity to the furnace hearth. I The products of 1 combustion which have then given up their availv 7. 5'5 l heat rise to the furnace arch and pass pfi 1- to the furnace gas outlet. The waste gases are free to pass beneath the furnace arch as no combustion is taking place in that zone.

Each fuel burner may be individually reguv lated as to fuel and air requirements depending upon the necessity of operation. The fuel bumv ers may be operated singly or in groups as fits the operating conditions best.

This method of firing results in all combustion "contact with the-furnace arch and furnace walls.

One advantage to be gained by this method of firing is a much longer life to the furnace structure due to a lower temperature of the gases in contact with the structure and less concentrated velocity along parts of this structure. This method of firing spreads the smelting zone over a much larger area of the furnace than is possible in the past practice. The smelting zone will be at a lower temperature and thus increase the life of the furnace structure. The fact that the temperatures of the furnace arch and walls will be much lower than in past practice results in lower heat radiation losses through the structure.

We believe that this is the first method of firing which places the maximum temperature upon the charge and the minimum temperature upon the furnace structure.

Ore smelting furnaces using nozzle burners for oil, gas or powdered coal, have generally been of rectangular shape with the burners at one end and with their width forty per cent or less of their length. The present invention permits of the making of such furnaces of greater relative width and of all other shapes in plan; square, oval, ob-

- long, circular and so forth. Also with the present invention it is not necessary to provide special openings'through the furnace structure for the introduction of fuel. The fuel, with its air or oxygen for combustion, may be introduced through the regular charge openings.

The invention is described herein particularly as applied to the smelting of copper ores (generally concentrates) for the production of matte. It is applicable, however, with advantage to various other metallurgical operations involving the smelting, melting or heating of the charge in a covered furnace. The accompanying drawings illustrate several designs of furnace suitable for carrying out the process.

Fig. 1 is a broken plan; Fig. 2 a longitudinal section and Fig. 3 a cross-section of a copper smelting reverberatory furnace; Figs. 4, 5 and 6 are partial cross-sections of alternative designs; Fig. 7 is a complete cross-section of another design; Fig. 8 is a horizontal section of a furnace circular in plan; and Fig. 9 is a diametral section of the same on the line 99 of Fig. 8.

Referring to Figs. 1 to 3,,the furnace is of the elongated shape of the common copper reverberatories, having a hearth H, side walls I2, a rear end wall I 3 and an arched roof it, forming a sort of tunnel leading to a waste gas oif-take: orflue connection 55. Charge openings it through the'roof are provided along lines adjacent to the side walls and end wall, through which the charge is dropped intermittently and often enough to maintain it in piles along the side walls of a contour indicated roughly at ll (Figs. 2 to 7), sloping down from both sides to the center; accumulating on the hearth in the form of molten matte l8 and slag l9. Charging is carried on at a rate calculated to maintain the desired conditions within the furnace, while the products are removed, the matte being generally tapped periodically. The slag may be drawn oif continuously or at intervals.

Referring again to Figs. 1 to 3, burner openings 20 are provided in any suitable position as, for example, in a line along the upper part of each side'wall and the end wall 13, preferably staggered with respect to the charge; openings so as to project the flames between the'peaks of the charge piles. In the burner openings are nozzle burners 2| for gas or other fuel directed downward so as to project the mixture of fuel and air' upon the surface of the fresh charge so that the flame gases at substantially their hottest-point come into contact with the charge at substantially the coldest portion of its surface.

' The vertical distance between the surface of the .charge and the roof is comparatively short at the points or line of application of the flames, and increases with the transverse distance therefrom, leaving a comparatively large space for the expanding and rising gases beneath the central portion of the roof. .It is this distribution ofv the clear space, with reference to the point and manner of application of the flames, which serves chiefly to maintain the maximum temperature on the charge. From Figs. 1 and 2 .it appears that this method is pursued and the smelting effected throughout substantially the full length of the furnace. But the. smelting zone may be shorter, leaving a fairly long settling zone at the outlet end, as is common in copper reverbera-' lis.:taking place. Thence they rise in the man-.

tories.-

The flames sweep over the charge as-indicated at 22, Fig. 3, while combustion of the .fuel and air ner-indicated by the arrows 23 into the space provided under the roof I 4 after the gases have given up a large part of their heat, passing'finally out through the oflz'take l5. Thus there is a lower zone of maximum temperature adjacent to the surface of the charge and anupper zone of minimum temperature adjacent to the roof and to the upper portions of the side walls. The maximum amount of heat is thereby transferred to the charge in the shortest'possible time at the highest temperature of the flame, and the maximum capacity of the furnace is obtained under conditions of greatest economy.

Fig. 4 illustrates an optional location of the with the charge openings.

Fig. illustrates another optional arrangement of the burners 2! in openings 25 which are adjacent to the charge openings E6; the burners being directed vertically downward, instead of obliquely as in the other figures.

According to Fig. 6 a nozzle burner 26 of slightly different design directs a stream of fuel through a charge opening 16 in the roof. Air for combustion is sucked in with the fuel stream. A chute 27 is indicated for guiding the charge and a water jacket 28 for protecting the roof from too rapie burning out by the flame. The burner 26, and the same is true of the burners in the other figures, is adjusted to such a position as to bring the flame at its hottest into contact with the surface of the charge.

Fig. '7 illustrates a furnace of extraordinary width. It may be forty per cent of the length, or greater, for example, or even'wider than it is long (the length being measured from the outlet flue wall to theopposite end wall). The roof 29 is of the suspended type instead of the sprung arch of the other figures. Besides the charge holes 30 arranged alongthe side lines of the roof as in the previous figures, there is a row of charge holes 3! along the center. The charge therefore will be maintained in piles I! along the side walls l2 and also in piles 32 along the center line. Assuming the burners to be arranged as in Fig. 3, the flames 22 from the opposite sides will sweep over the surface of the charge and will be deflectedupward in the direction of the arrows 23 intothe space provided for them below the roof. The line of charge piles 32 along the center serves to positively deflect the flame gases upward. Fig. '7 shows the charge in molten condition at the surface, and this maybe the case at times and at certain parts of the furnace, though generally it is preferable to time the charging and drawing-off operations soas to show a portion of the solid charge floating over the surface of the slag except near the front where the slag is drawn oif. r

In the round furnace of Figs. 8 and 9 there is a circular sidewall 33 carrying a dome-shaped roof 34, with a gas ofitake 35 atits center and with a number of charge openings 36 around.- its rim. These openings carry charge chutes 31. Or charge openings 36 may alternate with openings 20 provided with burners 2| (as at the right of Fig. 9). Or each of the openings may be used both for charging and for a burner. Alternating with the openings 36 in the roof are openings 38 space under the roof and finally passing to the offtake at the center; or at any other suitable point.

Various other modifications in the design. of the furnace and in the ,modeof applying the process may be made by those 'skilled in the art without departing from the invention as defined in the following claims.

What we claim is: 1. In the smelting of ores and similar operations in a covered furnace, the method which comprises the charging of the ore in solid form through openings in the roof so as to maintain it in piles along the walls with the tops of such piles adjacent to the tops of the walls and ap- 75' plying all the heat in flames directed downwardly against the tops of the piles, causing the flames to sweep over the face of the charge while combustion is taking place and the waste gases to rise from the lower portions of the charge unobstructedly to the roof.

2. In the smelting of copper ores in a reverberatory furnace having charge openings along the sides of the roof, the method which comprises feeding the solid ore through such openings and maintaining it in piles against the walls sloping down toward the center and applying all the heat in flames projected downward through the charge openings so as to directly engage the piles of ore at their highest point and to sweep over the sloping face of the charge while combustion is taking place, the waste gases rising unobstructedly in the central part of the furnace from the lower part of the charge to the roof.

3. A furnace for smelting and similar operations having a roof and means for maintaining the charge in solid form in piles and having nozzle burners the orifices of which are close to and directed downwardly upon the upper parts of such piles so as to apply flames directly to the top and cause them to sweep over the faces of such piles, thespace within the furnace being unobstructed except by the aforesaid flames so that the waste products of combustion rise unobstructedly from the lower part of the charge to the roof.

4. A reverberatory furnace for smelting copper ores having charging openings at the sides of the roof permitting the maintenance of solid ore in piles along the walls and extending up nearly to the tops of the walls and nozzle burners having their orifices close to the tops of such piles and directed downward so as to apply flames directly to the surface and causing them to sweep over the charge while combustion takes place.

the furnace being unobstructed within so that the waste gases of combustion can rise unobstructedly to thereof.

5. The reverberatory furnace of claim 4, the nozzle burners being located within the charge openings.

6. The reverberatory furnace of claim 4, the nozzle burners being located in the upper portions of the side walls.

'7. The reverberatory furnace of claim 4, the nozzle burners being staggered in relation to the charge openings.

ENOCH A. BARNARD. HUGH J. MAGUIRE.

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