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Feb. 1, 1938. 2,10?,255 P. MccoMB METHOD OF TREATING CARBONATES Filed Sept. 4, 1934 I Parker . Z M? 60/77 5, Patented Feb. 1, 1938 2,107,255 UNITED STATES PATENT OFFICE 2,107,255 METHOD OF TREATING CARBONATES ’ Parker McComb, Monroe, La. Application September 4, 1934, Serial No. ‘742,624 1 Claim. (Cl. 263—-53) top of the stack, it is formed in the shape of a This invention relates to the reduction of minerals and ores to oxides and by-product gases. hollow cylinder. It is an object of my invention to provide a roasting oven which will roast stone or ores with Located inside the stack 2, there is a roasting chamber 3, which is uniformly rectangular in 5 out permitting the stone, at any place in its cross sections throughout its entire length. This chamber is anchored along its. narrow faces to the stack 2 from points 4 down to the bottom of the stack 2. From the bottom of the stack 2 to points 4, gas spaces are provided between the wide faces of the roasting chamber 3, and stack 2. To prevent any distortion of the roasting chamber which might result from the condition of high combustion temperatures, it has been found advisable to anchor the roasting chamber 3 along its narrow faces to the stack 2. From travel through the oven, to come into direct con tact with the products of combustion. A further object of this invention is to provide a roasting oven with a vertical type roasting 10 chamber in which the material being roasted may be lowered as a unit. Another object of this invention is the pro vision of a roasting oven having a hopper lo cated in the path of the products of combustion 15 whereby to dry the charge. Another object of this invention is to provide points ll, upwardly, with the exception of the an improved process of burning stone, ore or the area at the discharge manifolds 5, the roasting chamber 3 is spaced from the stack 2 on its like, and to separate the resulting by-product gases by allowing them to stratify according to 2 O their various speci?c gravities. Other objects and advantages of my invention will be apparent during the course of the follow ing description. . In the accompanying drawing forming a part 25 of this application, and in which like numerals are employed to designate like parts throughout 30 narrow faces as well as its wide faces to permit products of combustion to contact a greater heat ing surface. - The roasting chamber 3 is to be constructed out of suitable refractory materials having a high thermal conductivity value, such as alu minum oxide, beryllium oxide, thorium oxide, silicon carbide, zircon, or from metals such as the same, Fig. l is an elevation view in part section of a tungsten, molybdenum, etc., having high melting roasting oven embodying my invention, Fig. 2 is a cross sectional view of the same on line 2—2 of Fig. 1, structed by superimposing individual tiles, one on another, and cementing them together. Numeral 5 designates discharge manifolds. Fig. 3 is a cross sectional view of the same on These manifolds are fabricated from the same line 3—3 of Fig. 1, Fig. 4 is a cross sectional view of the same on 35 line 4-4 of Fig. 1, Fig. 5 is a cross sectional view on line 5-5 of Fig. 1, showing details of a valve feature of this invention. In the drawing wherein, for the purposes of 40 illustration, is shown a preferred embodiment of this invention, numeral I designates the foun dation of the same. The foundation is fabricat ed from structural steel or other suitable build ing materials and is designed to hold up the oven 45 to a sui?cient height to permit dump carts or points. The roasting oven is preferably con materials that the roasting chamber 3 is fabri cated. These manifolds 5 may be cast as units but are more preferably constructed in some 35 superimposed hollow tile construction followed in the construction of the roasting chamber 3. Exhaust ports 5 are provided in the narrow walls of the roasting chamber 3. These ports are slanted upwardly so that they can not get clogged 40 with stone. Numeral l designates discharge pipes through which the generated gases may be drawn off by means of a pump not shown. Numeral l0 designates a funnel shaped load other type conveyors to be passed under the ing hopper. ‘The loading hopper I0 is supported oven to receive the ?nished product. The outer wall, forming the stack 2 of this oven, is con on the top of the stack 2 by means of a frame I I. structed of ?re brick throughout its entire length. 50 However, other types of material may be substi tuted for ?re brick toward the top of this oven where the heat is less intense. From the foun dation l, upwardly to line :1:—a:, the stack 2 of this oven is made in the form of a hollow rec 55 tangular prism. From line :c-—r upward to the 45 The loading hopper l0 terminates at its lower end in a rectangular spout I2, which is made smaller than the mouth of the roasting cham 50 ber 3, into which it extends to provide a clear ance space through which waste gases may be ?oated o?. _ As the temperatures at this part of this oven are not extreme, I make the loading hopper 55 2 2,107,255 l0 out of metal of high thermal conductivity ' is supplied with stone or the like from the hop per H]. The roasting chamber 3 should be kept values. The apron HIa of the loading hopper It may be provided with ports Hlb opening upward and , outward so as to allow escape of waste gases from the raw material as it is being dried and heated. The furnace structure proper of the stack con sists in the rectangular brick work of the stack 2 from its ?oor up to line x--.r, and is designated 10 by numeral l3.’ Through holes I4 in the oppo site narrow walls of the furnace I3, are mounted burners 15. These burners are mounted, pref erably, in such a position thatthe flames com ing from them strike the roasting chamber 3 at right angles on its broad faces. While most of the combustion takes place in the furnace l3, it is true that, under some conditions, some of the combustion takes place at points higher up in the stack 2. To insure complete combustion, adjustable dampers l6 (see Fig. 5) are provided in the ?oor of the furnace l3 to admit excess air when needed. It has been found advantageous to carry the burner feed lines l1, both fuel and air, through the furnace so that both the air and fuel may be preheated for the sake of econ omy and for the sake of producing higher burn ing temperatures in the burner ?ames. Referring to Figs. 5 and 1, numeral I 8 desig nates a take-off hopper and 19 a metering valve mounted at the extreme lower end of the take-off hopper to enclose the same. The metering valve I9 is of a cylindrical shape and is provided with longitudinal pockets 20. ~ When the metering valve I9 is rotated, the measures of stone that settle into the pockets 20 are passed out and allowed to fall by gravity into some suitable container or onto a moving con veyor. The stack 2 is provided with suitable peep transfer of the heat from the ?ue gases to the charge through the metal hopper. The hopper’ is made out of an efficient heat conducting'metal, 10 whereby, to more effectively use the waste heat of the escaping ?ue gases. The valve 20 at the bottom of the take-off; hopper acts as a closure for it. Through the means of pockets 20 in the surface of the valve, 15 de?nite quantities of the burned charge may be metered out as the, valve is revolved. In this way the entire chargein the roasting oven is gently lowered. As the roasting oven 3 is ver tical, the force of friction of the roasting oven’s 20 walls on the charge will be too slight ‘to stir up the charge, with the consequence that the entire charge in the roasting chamber 3 may be lowered as a unit. ' > . The heat necessary to reduce the charge to oxides and the by-product gases, S02, CO2, etc., is supplied by burning fuel through means of burners I5. Gas or oil are excellent fuels to use in this oven ‘because the combustion of these ,_ fuels may be readily controlled. However, I do'v 80 not limit myself to these fuels since my oven may be ?red with other fuels successfully. In the operation of, the preferred?form of this oven, ?ames from the burners 15 are directed, against the opposite broad faces of the roasting v'35 chamber 3. This is the hottest point in the oven. The fuel and air supplies, as previously explained, are preheated to effect a higher temperature than would ordinarily occur from the burning holes 2|, through which the temperatures of the of a mixture of cold fuel and air, since the heat ‘14.9 products of combustion may be observed at the various points of its travel. ‘This oven may be constructed in various sizes,’ depending on the volume or materials to be treated, or may be constructed in a battery of requisite to bring the‘mixture up to the ?ash units. It has been found practical that an oven .of .this type 30 to 40 ft. in height will provide su?icient contact surface for the preheating and the separation of gases, complete burning of the raw material, and also provide a preliminary cooling chamber in the oven. The burner should be placed at about one-fourth the height of the oven, the ports at about two-thirds to three fourths of the height of the oven. Among the ores and minerals that can be burned, roasted, vitri?ed, disintegrated, reduced or fused in the oven, are: galena, sphalerite, point has been already partly supplied vto the fuel and air themselves separately. ' - To insure complete combustion, excess air'is admitted through the ?oor of the furnace to the 1145" stack 2 by means of dampers I6. An occasional baffle member 2b may be extended inwardly from the stack’s inner Wall into the ?ue to- create eddies and prevent the ?ue gas from channel ling and passing out without giving up its heat. The temperature in the furnace portion l3 of the stackv 2' and the other portions of the stack and the resulting temperature in the roasting chamber 3 itself will depend on' the material being treated and the length of time such mate 55 rial remains in the oven. 7 > For example, the temperature range necessary chalcopyrite, chalcocite, pyrites, gypsum, cerru to reduce normal ‘carbonates inside the roasting site, smithsonite, limestone, marble, malachite, azurite, magnesite, dolomite. The principal by product gases given off by the above named mate chamber 3 proper would ‘have to be'from 1200° F. to 3000° F. to produce metallic oxides and C02. 560 The temperature‘ of the ?ue gases leaving the rials are sulphur dioxide (SOz),'having a spe stack should be maintained at about 200° 'F'. ' ' . ci?c gravity of approximately 2.2, and carbon dioxide (CO2), having a speci?c gravity of ap At no place in the stack 2 are the products of combustion allowed to come in direct contact with the charge itself. All of the heat that the? charge in the roasting oven 3 receives from the combustion of the fuel has to pass through the walls of the roasting chamber 3. This feature 65 proximately 1.5 as compared with air. The ore or mineral’ to be treated is ?rst crushed to a size that will permit it to be readily attacked by heat. Generally, a ?neness that will pass a 70 ?lled and an extra supply of the stone or the like should be held in the hopper. As the ?ue gases issuing from the stack 2 must, 5 by design, impinge on the hopper, the portion of the charge in the hopper is heated by the one or two inch screen is sufficient. If the ore or mineral to be treated isto- be acted on with a reagent, oxide or silicate, this oxide or silicate or other agent is then mixed with the stone charge either before or after crushing. » r of our invention is very important since it insures ' againstany contamination ofv the charge from 70 the fuel. 7 ~ From the drying zone A, where the charge is dried in the hopper by the'esrcaping ?ue gases, the charge passes into a preheating zone B at In operating my oven, the roasting chamber 3 ‘ the top of the roasting chamber. In-zone'B “18.3575 2,107,255 charge is being heated both by the heat from the ?ue gases and also by ascending gases which have been generated lower down in the roasting oven 3. In the preheating zone B, exhaust ports 6 provide communication between the roasting oven 3 and the discharge manifolds 5, provided with discharge pipes 1, whereby the gases gener ated in the roasting oven 3 may be drawn o?. In the generation of S02 or CO2, which have 10 greater speci?c gravities than air moisture and the other gas impurities, the flow from the ex haust pipes may be so restricted as to build up the level of the column of S02 or CO2 with a resulting increase in pressure to such an extent 15 that the gas impurities, and even a part of the $02 or CO2 may be ?oated up and out of the roasting chamber 3. Since the CO2 gas which is generated at the bottom portion of the vertical retort is heavier than the air and moisture in 20 the portion of the charge at the top portion of the retort the volume of CO2 gas and volume of air and moisture will remain separated along a natural level in the absence of any stirring action. To assure that there will be no stirring action during the carrying out of this process the charge of ore that is being heated is lowered as an un disturbed unit. That is to say the individual lumps of ore in the charge stay in their same relative position with respect to one another dur ing their entire travel through the oven. This type of operation of our oven will insure the pro duction of a very pure gas. As the charge is 3 When the temperature of the burners is held constant, the entire regulation of the furnace resolves upon the regulation of time under which the charge is subject to the constant temperature. The time element is determined by the rate of ?ow of the charge which is in turn regulated by the metering valve [9. And so I say that, with a constant temperature maintained, the degree to which the charge is burned may be controlled 10 by regulating the meter valve l9. To insure the purity of the by-product gases, care must be taken when drawing off the by product gases to maintain su?icient pressure in the preheating zone B at the ports 5, so that no down draft is created in or through the top por 15 tion of preheating vzone B above ports 5 and to maintain a proper separation zone between the generated by-product gas and the gas impuri ties. It is to be understood that the form of my 20 invention shown and described is to be taken as only a preferred embodiment of the same, and that various changes in size, shape and arrange ment of parts may be resorted to without depart ing from the spirit of my invention or the scope 25 of the subjoined claim. Having thus described my invention, I claim: lowered past the exhaust ports 5, any generated The method of treating carbonates, comprising applying heated products of combustion to the exterior of a vertical retort having its upper end open and in free communication with the at mosphere so that the heat applied to the retort decreases upwardly for a?ording a lower reduc gas which was trapped in the voids of the charge may be drawn off along with the ascending stream ing zone and an intermediate pre-heating zone and an upper drying zone, introducing a 35 of generated gas. After the charge has passed down through the preheating zone B, it enters into the reducing loose charge of a carbonate comprising aggre gates which are approximately one-inch to two inches in size and having voids between them into the upper open end of the retort and grad zone C in the oven, where the charge in the roast ing chamber 3 is burned, fused, vitri?ed or otherwise reduced. When a charge of normal carbonates is used, it will be completely reduced in this zone to its metallic oxides and. CO2. In leaving the reducing zone C, the charge 45 passes through the cooling zone D, preparatory to entering the take-off hopper l8. In cooling, the charge gives up part of its heat to the incom ing fuel and air being brought to the burners. From the cooling zone D the charge, now the ?nished product, enters the take-01f hopper I8, which, as previously explained, is closed at its bottom by a metering valve l9. The metering valve 19 is intended to be rotated 55 by a gear or like means and its speed to be con trolled by a suitable control means so that the down ?ow of the charge may be uniformly con trolled. ually moving the charge downwardly through 40 the retort so that it is subjected in succession to the action of heat in the drying and pre-heat ing and reducing zones, discharging the gases from the charge in the drying zone upwardly through the open end of the retort, preventing 45 any substantial amount of gases other than car bon dioxide gas from entering the pre-heating zone by causing a portion of the carbon dioxide present in the pre-heating zone to pass up wardly through the voids in the charge in the pre 50 heating zone and drying zone and thereby forc ing other gases through the voids in the drying zone and ?nally discharging to the atmosphere through the upper open end of the retort, and withdrawing a portion of the carbon dioxide from 55 the pre-heating zone. PARKER McCOMB.