US2387882A

US2387882A - Process and apparatus for roasting and reducing iron oxide and other oxide ores

Info

Publication number: US2387882A
Application number: US492732A
Authority: US
Inventors: Clark Walter Gordon
Original assignee: CLARKIRON Inc
Current assignee: CLARKIRON Inc
Priority date: 1943-06-29
Filing date: 1943-06-29
Publication date: 1945-10-30
Anticipated expiration: 1962-10-30

Description

Oct. 30, 1945. w CLARK 2,387,882

PROCESS AND APPARATUS FOR ROASTING AND REDUCING IRON OXIDE AND OTHER OXIDE ORES Filed June 29, 1943 fl a? .I. Wx 47/ M l i w Patented Oct. 30, 1945 PROCESS AND APPARATUS 'FOR ROASTING AND REDUCING IRON OXIDE AND OTHER OXIDE ORES Walter Gordon Clark, Los Angeles, Calf., assignor to Clarkiron, Inc., a. corporation of Nevada.

Application' June 29, 1943, Serial No. 492,?32

' 6 Claims.

My invention relates to a process and apparatus for roasting and reducing iron and other oxides and oxide ores, and more particularly to one in which the heat generated in the manufacture of the gases used to roast the ore aids in the manufacture of the reducing agent used to reduce the oxides or ores, and at the same time substantially aids in the necessary heating during the reduction of said oxides or ores by said reducing agent.

Hydrocarbon gas, natural or manufactured, is broken to Hz and C. The C is recovered and Hz is used as the reducing agent. In my invention, all iron ores, including magnetite, can be usedthus permitting recovery of iron and oth'er metals from magnetic oxide ores.

One of the purposes of my invention consists in burning natural gas with a limited amount of air to form water vapor and carbon monoxide (HzO and CO). This heated gas is then burned to CO2 to roast 'the ore and at the same time 'the heat of combustion to CO is used to break other hydrocarbon or natural gas, mostly methane, into carbon and hydrogen (C and Hz). Th'e carbon is deposited on the surface of the heated chamber, scraped off, and recoverable as a byproduct while the hydrogen (Hz) is used as the reducing gas to reduce the oxide ores.

Other advantages of my invention will be ap parent from the following specification and drawing of the preferred embodiment of my invention.

In the drawing:

Figure 1 is a longitudinal section of th'e lower part of my roaster and reducer.

e bustion chamber 3. Air in the proper proportion to burn this natural gas to carbon monoxide and Water vapor is admitted through a surrounding pipe 4, which is concentric with the pipe l but of larger diameter and attached thereto. Gas and air is admitted through the ports 5 into the combustion chamber 3. I provide a lighting port 6 from the outside of the furnace extending into the combustion chamber 3, through which any lighting mechanism can be inserted to ignite the gases in the combustion chamber 3. The partially burned or reacted gases pass from the combustion chamber 3 through the stack 'I past the butterfly valve 8 into a roasting chamber 9. In this chamber the carbon monoxide (CO). is burned to carbon dioxide (COz) by the admission through a valve o of air. Further natural or hydrocarbon gas can be admitted through a valve li to aid in preheating the roasting furnace. After the roasting furnace has been sufliciently heated to roast the ores, the valve H can be closed and merely the gas entering through the stack 'I and further supply of air used to roast the ore.

I provide the roasting chamber 9 with a series of downwardly pointing truncated cone segments z and a series of upwardly pointing cones !3. The upwardly pointing cones I3 are of greater diameter than the openings in the downwardly pointing truncated cones and are given a vertical reciprocating motion adjustable as to the magnitude and the frequency of the movement. The

magnitude and the frequency of the movement are adjusted to the rate at which the ore is roasted and reduced.

The downwardly pointing truncated cones 12 are firmly set in the brick lining |4 of the roaster. The upwardly pointing cones |3 are segments assembled loosely on the vertical shaft |5 and each segment loosely attached to the vertical shaft by the collars 16. Each set of cones |3 can 'move to a stop on the fixed cones l2 or may stop on granules of ore under the cone and limit the movement of the cone segments but permit the vertical shaft |5 to move to a greater extent through the cones I3. The vertical motion is generated by any type of hydraulic pressure or pneumatic pressure in a cylinder or by a reciprocated motion generated by a crank or an eccentric.

On the upward limit of the movement of the cones l3, the flow of ore to be heated or roasted is shut off by the top cone I' substantially contacting the lower end of a vertical loose cylindrical feed chute |8 through which the ore is fed to the roaster. On the downward movement, the cones |3 contact the next lower downwardly pointing cone, interrupting the flow of material. On the next upward movement, the previously admitted material is released and fiows by gravity down the fixed cone !2 to the next upwardly pointing cone l3, thus allowing the ore to move downwardly a, short distance and stop on each stroke while additional ore is entering at the top of the roaster.

The cones l2 are set at an angle greater than the angle of repose of the ore permitting the ore or granular material to flow on these cones by gravity. The movable or upwardly pointing cones |3 are set at a lesser angle or slightly less than the angle of repose of the ore under treatment. Thus, the ore rests on the upwardly pointing cones until moved downwardly by the reciprocating motion of the cones l3, and when discharged from the movable cones to the fixed cones l2 the material moves 'down the fixed cone by gravity. All cones I 2 and !3, except the top and the bottom cones I'I and l9, respectively, are equipped with fiues 20 projecting above the cone a greater distance than the depth of the ore on the cone. These flues 20 permit free movement of heat from the burners as the products of combustion move upwardly from' the stack 1, thereby heating the cones and subjecting the ore thereon to a heating and roasting treatment. These flues may be set at an angle to direct the heated gases to move on a. circular or spiral path. The bottom cone s, below the point at whichthe combustible gases enter the roaster, is positioned to allow the roasted ore to move downwa'dly on the sharper angle of this cone by gravity into the reduction chamber 2 I. The cone I 9 is positioned to permit gases rising through the ore in the reduction chamber to pass horizontally through the ore to an independent discharge outlet 22 for further use; or upon closing the outlet 22 the gases rising through the ore will mix with the gases from stack 1 and burn in the roaster.

The heated comb-ustible gases enter the roaster below the bottom .cone 19 and the gases move through the fiues in the stationary and movable cones |2 and |3 -upwardly to a. stack 23 or vent, through which they are discharged to the atmosphere, producing draft as required.

To provide a reducing'gas for the reduction of the roasted ore moving downwardly through the reduction chamber ZI, I admit natural gas or other hydrocarbon gas through the valve 24 to the chamber 25, which is on the exterior side of the combustion chamber 3 and separated thereby by a metallic wall 26. The heat of combustion of the natural gas and air in the combustion chamber 3 passing through this wall 26 and the heat' of the reduced ore in the annular chamber ZI is sufiicient to break the natural gas (which is principally methane (CHQ) in the chamber 25 to hydrogen (Hz) and carbon (C). The carbon either falls free down to hopper 21 and into spilet 22 for further use and not pass up through the master. I provide pyrometers 3| to record the temperatures of the reducing gas in the stack 21.

To reduce friction on the walls of the reduction chamber 2I, I have given the walls an angle of approximately 4%, making this chamber of greater area at the bottom. To provide for vertical expansion, a trap 32 is provided at the upper end of the stack which fits over the outer wall 33, allowing the stack wall to move therein. A gas-tight expansion joint or bellows 35 of any type can be placed to connect the main body 36 of the rcaster to the outer wall 33 of the reduction chamber. To provide support for stack 'l in the center of the reduction chamber 2l, projecting supports 34 are attached to stack 'I and rest on an ofi'set in the outer wall of stack 2l. Stack 1, combustion chamber 3, and the cover of gasbreaking chamber 25 are Suspended from supports 34. The outer wall of chamber 25, the outer wall 33 of stack 2l, and the weight of ore and metal in ZI are supported on feet 31 resting on plate S, which expand upwardly.

While I have described the prefe'red embodiments of my invention, I am not limited to any of the details set forth therein except as specifically described in the appended claims.

I claim:

1. In the combination of an ore roasting and reducing furnace, means to supply ore to said roasting and reducing furnace, a combustion chamber wherein hydrocarbon gas and air are burned to form a roasting gas, a chamber surrounding said combustion chamber wherein natural gas is broken into hydrogen and carbon to form a reducing gas by the heat of combustion in said combustion chamber and the heat of the reduced ore, a roaster into which the roasting gas from said combustion chamber is further burned with air, a series of fixed downv wardly sloping cones in said roaster. a series ral discharge 28, where it is drawn off, or the carbon from the broken gas is deposited on the walls 26 and scrapedtherefrom -by a, revolving scrape' 29, then falling down into the hopper 21 and the spiral discharge 28.

The hot Hz or reducing gas then passes through opening 40 into the reduction chamber 2l where it encounters the ore descending from the roaster. At the same time, the ore and gas are heated up to a temperature substantially around 1850. F. by the induction coils 30, and heated to 1950 F. by combustion of the gas to CO. At this and lower temperatures the hydrogen reduces the oxide ores to metal and water vapor, and the vapor and excess Ha pass up through the reduction I chamber 21 and the discharge outlet 22, the reof vertically movable upwardly sloping cones concentric with said downwardly sloping cones. the movement of said upwardly sloping cones permitting ore admitted to the top of said cones to move downwardly over said cones until discharged down into a reduction chamber into which the reducing gas is admitted and where said ore in reduced by said reducing gas, and ports over each cone for passing said roasting gas.

2. In the combination of an ore roasting and reducing furnace, a combustion chamber wherein natural gas and air are burned to form a roasting gas, a chamber surrounding said combustion chamber wherein natural gas is broken into hydrogen and carbon to form a reducing gas by the heat of combustion in said combustion chamber, a roaster into which the -roasting gas from said combustion chamber is further burned with air, a series of fixed downwardly sloping cones in said roaster, a series of vertically movable upwardly sloping cones concentric with said downwardly sloping cones, the movement of said upwardly sloping cones permitting ore admitted to the top of said cones to move downwardly over said cones until discharged down into a reduction chamber into which the reducing gas is admitted and where said ore is reduced by said reducing gas, ports over each cone for passing said roasting gas, and a valve for neutralizing the pressure of the roasting gas and the reducing gas at the entrance to said roaster.

3. In the combination of an ore roasting and reducing iurnace, means to supply ore to said roasting and reducing furnace, a combustion chamber wherein .natural gas and air are burned to form a roasting gas, a chamber surrounding said combustion chamber wherein natural gas is broken into hydrogen and carbon to form a reducing gas by the heat of combustion in said combustion chamber and heat in the reduced ore with means for passing the reducing gas into contact with the ore under reduction, a roaster into which the roasting gas from said combustion chamber is further burned with air, a series of fixed downwardly sloping cones in said roaster, a series of vertically movable upwardly sloping cones concentric with said downwardly sloping cones. the movement of said upwardly sloping cones permitting ore admitted to the top of said cones to move downwardly over 'said cones until discharged down into a reduction chamber into which the reducing gas is admitted and where said ore is reduced by said reducing gas, the outer walls of said reducing chamber sioping outwardly from the vertical to reduce friction in said reducing chamber, and ports through each cone for passing said roasting gas.

4. In the combination of an ore roasting and reducing fumace, means to supply ore to said roasting and reducing furnace, a combustion chamber wherein natural gas and air are burned to form a roasting gas, a chamber surrounding said combustion chamber wherein natural gas is broken into hydrogen and carbon to form a reducing gas by the heat of combustion in said combustion chamber and the heat of the reduced metal, a master into which the roasting gas from said combustion chamber is further burned with air, a series of fixed downwardly sloping cones in said roaster, a series of vertically movable upwardly sloping cones concentric with said downwardly sloping cones, the movement of said upwardly slopng cones permitting ore admtted to the top of said cones to move downwardly over said cones until discharged dom into a reduction chamber into which the reducing gas is admitted and where said ore is reduced by said reducing gas, and ports over each cone for passing said roasting gas, and a heater surrounding said reduction chamber.

5. In the combination of an ore roastng and reducing furnace, a combustion chamber wherein natural gas and air are burned to CO to form a combustible gas for roasting, a chamber surrounding said combustion chamber wherein natural gas is broken into hydrogen and carbon to form a reducing gas ,by the heat of combustion in said combustion chamber, a roaster having therein a series of fixed downwardly sloping cones, a series of verticaly movable upwardly sloping cones concentric with said downwardly sloping cones, the movement of said upwardly sloping cones permitting ore admitted to the top of said cone structure to move downwardly over said cones until discharged down into a reduction chamber into which the reducing gas is admitted and where said ore is reduced by said reducing gas, and ports through each cone for passing said roasting gas.

6. In the combination of an ore roasting and reducing furnace, means to supply ore to said roasting and reducing furnace, a combustion chamber wherein natural gas and air are burned to form a roasting gas, a chamber surrounding said combustion chamber wherein natural gas is broken by heat into hydr'ogerr and carbon to f orm a reducing gas by the heat of combustion in said combustion chamber and the heat in the reduced ore, a roaster in which ore moves downwardly and is roasted by said roasting gas, a reduction chamber into which said roasted ore moves down and into which the reducing gas is admitted and where said ore is reduced by said reducing gas.

WALTER GORDON CLARK.