US2991987A - Processes for heating a mining liquid and mining therewith a substance modified by heat - Google Patents

Description

UnitedStates Patent .PROCESSES FOR HEATINGHA rMINING LIQUID AND f MINING THEREWITH A SUBSTANCE MODIFIED. BY' HEAT K Robert Y. Heinze, Hammond,"lnd., a'ssignor to Submerged Combustion, Inc., Hammond, Ind., a corporation of *Filed Dec. 31,'1956, Ser.- No. 631,870 '4 Claims. (Cl. *M2-3) This invention=relatesto new andimproved processes fifor' direct'introduction of heat intofmaterials andv Yto the utilizationithereof in'the mining or -separationof sulfur and other heat-modifiable substances.

Theusual method by whichsulfur is mined is toforce hot` water, vheated in conventional lboilers, into yacon- 'duit which is positioned inthe sulfur-bearing ore body. The' conduit is-provided :with perforationsin Vitsfside walls 2adjaceiit the endA which is in rthezsulfurrbearing orebody. A? halideI i'sjlprovided between Ethese perforations. and other penforations farther'down fin the side 'wall of the yconduit wso that the vhot yfwaterilows into Athe sulfur-bearing ore body' where Vthe .heat 'inthe-water is transferred to` the sulfur, which then becomes-molten. 'Because it( is heavier than'the water, the "molten sulfur gravitates' downwardly `audiows into Vthe perforations in the Vcor'iduitabelow the -baie.f'l`he molten sulfuriin they lower end ofthe vcouiduitis conducted tothe surface by means ofanother'conduit disposed centrally within the frstfconduit. Athird 'conduit `containing compressed vgas is dispo'sed"centrally in the vsecond conduit, yand the columnof molten 'sulfur jinside the second conduit 'is lifted to the surface by means of the `compressed gas. y

Thisv process is made costly v"by thefact v`that-*the h'ot water'isheated vin Vconventional type boilers. That is yto say, the water is heated by the transfer of the heat of combustion through metallic walls. Furthermore, .the 4fair isseparately compressedl `and then released without havingrendered any other'tunction than 'that of-lifting the molten' sulfur from'subsurface 'regions'tothe surface AWhere it is handled for further disposition. One factor in the high cost is that fresh, carefully treated wateris essential in conventionalptype boilers. Additionally, even with'fresh water, the water depositsscale on the metal surfaces which must be' cleanedfat `frequent intervals lin order to facilitate heat transfer through the'metallic walls ofthe boiler.

It is an object of this invention to provide economical processesifor heating by directheat exchange.

A further object is to provide processes wherein brack- .ish, alkali, orsalt water may be heated.

A further object is to j provide economical processes .for heating'mining water wherein Ya variety of different .kinds of heating fuels maybe used.

:A still further object is to provide methods wherein moltensulfur may be used as amining liquid.

Another object is to provide processes for mining sulfur.

Stillanother object is to. provide processes for utilizing brackish, a1ka1i,lor salt water in mininga heat-modiable substance.

A still'further object is` to providemethods yfor mining lor. separating from accompanying gangue materials substances su'ch asheav'y oils,'asphaltsfmetasand"other iceN vliquetiable or gasiable materials `either beneath orabove the earths surface.

Another object-is to provide processes for-the introduction of heat vby `direct .contact with .hot gasesfintoia moving materialand conducting 4theheat in -the moving material into other secondary-'stationary or movingemaiterials ina manner that permits separationof combustion gases and vapors before thc-.secondary releaseofheat `temperatureby direct-heat'. exchange With i afpreheatd gas, usually including the products of combustion. -f The heating-fuel' may be' anyof the combustible gases-Keombustible liquids, combustible .solids such as coaly particles, mixtures of gasesand vaporsgor liquids *admixedwith solid particles. Y After the Vgasres'havesbeen heatedfthey, 'and usually the'y products of combustion, fare passed into abody of ahe'ati'ng liquid in' whichtdirectheatexchange occurs. Theh'eating liquid maybe molten sulfur,\mo1ten metals, mixtures of moltenmetals, or highvboilingliquid hydrocarbons having a relatively highl'fiashlpointzsuch 'as petroleum, stocks. After the f gaseshave passed through lthe heating liquid, -they are withdrawn. from the direct heatexchange vesselfand recycled for `reheatng. rExcess gasesproduced through combustion are Withdrawnand preferably sent to a'lheat economizer for preheating feed water or other processing .liquids or materials.

, The Aheating yliquid is pumped from' the heating vessel "to a secondvessel containing b'oth the'heating'iuidand `a liquid to be heated. Direct heatexchange oecurslbetween the two liuids. The ytwolluidsmay beimmisci'ble and thus separate 1into two layers, i or they Amay tbe separated after heat exchange by vaporization of Aone,r of the uids. ,In the case of 'sulfurasthefheating liquid and Water as'the mining liquid, the two liquids separatethe sulfur as the lower "layeruand Water as the=upper layer. A level control valve or other regulating-device provides for the Withdrawal' of =the heating liquid, whence it is recycled'to the 4iirst'heatir'ig vessel. Also, 'a regulating device provides forwithdrawal of the.v desired amount of the uppervlayer of liquid. The second heating vessel is provided with pressure release Vapparatus for withdrawing Isteam from the vessel. Highpressure 'air Vvis obtainable by using steam'flashed'from the secondvessel. This .steam .is free from iixedgases and canbe used todrive Va high pressure air or gas compressor without going through a reheater and withouttthe difficult separation of ttixed gases and steam priorto using steam todrive A'the compressor. The compressed air or. gas ispumped into the mining zone to aid Yin lifting theV molten` mined. sulfur to the surface. Where sulfur is burnedas the fuel, .the compressed sulfur dioxide gasimay 'belcolleeted as liquid jsulfur dioxide or maylbeused in the manufacturelofsulfurie acid. .i Inmining yofheat-modifiable; substancesw'such asfsulfur,- thef'heated liquid s then pumped into the sulfurbearing strata ywhere it serves to heat the sulfur as previously described. The mining fluid pumped into the well is replaced by preheated feed water fed either into the top of the second heating vessel or below the surface of the heating liquid in the second vessel, as is desired.

The invention is illustrated in FIGURE l by schematic diagram. The apparatus comprises an inert gas heating chamber having a combustion chamber 12. In the burner illustrated wherein a fuel gas such as natural gas or other suitable type of fuel gas is used, the apparatus 'has arpilot gas conduit 14"and a main gas conduit 16. Support for 'combustion is provided through a main air conduit 1'8 and a pilot air conduit 19. The heated gases and products of combustion are forced into a irstheating vessel 20 below the surface of the heating liquid. 'Ihe -hot gases pass through the body of heating liquid, such as'sulfur, in direct heat exchange therewith and are with- -drawn fromthe heating vessel 20 in any one of several lfways. Thegases. may be recycled throughblower 22 for rehearing and recycling through the heating vessel 20. Alternatively, the gases may be withdrawn from the vessel 20 into compressor 24 and pumped into the well to serve as the lifting gas for the mined molten sulfur. In either instance the inert gas may be mixed with air supplied in the takeoff lines. In the case of the gas recycled through 'blower Z2 the oxygen in said air is employed to oxidize the sulfur or other heating liquid in the heating vessel 20T-thus providing additional heat to said heating liquid. Air may also be mixed with the inert gases used as the lifting gases; the air in this case functions in the customary manner. K

YExcess gases are released through the pressure regulator valveand may be passed to heat economizer I26 wherein they gases flow upwardly through packing in the heat ,economizer and counter-currently through downwardly flowing feedfwater. The feed water is thus preheated by i vthe gases. The cool gases are then released to the atmosphere or, as circumstances may warrant, they are processed through conventional apparatus for further conservation of material.

The preheated feed water is pumped by pump 28 into water heating vessel 30. The feed water may eitherbe fedunder the surface of the heating liquid or sprayed in near the top of the water heating vessel 30. The heating vessel 30 is a pressure vessel. Steam produced by the heat exchange between the heating liquid and water is *1 taken off to drive the compressor and for any other power `or heating purpose as may be desired. Excess steam is Ypassed to the heat economizer in a manner similar to the lexcess gases. A pressure safety pop-olf valve is provided on the vessel 30 to prevent build-up of excessive steam l.

The superheated mining liquid in pressure vessel 30, in

mosty instances water, is pumped by pump 34 into the casing of the heating well. It passes down the annular chamber 36 and into the sulfur-bearing strata through perforations as illustrated. The molten sulfur, being heavier than water, sinks to the bottom of the sulfurbearing strata and is drawn into the bottom chamber 38 and is then lifted to the surface of the well through annular passage 40 with the assistance of the lifting gases -which are pumped into the well through conduit 42. The molten mined sulfur is deposited in a sulfur storage pit.

Preferably, the molten sulfur is moved at temperatures either between its melting point, about 235 F., and 340 F. or above 446 F. At- 340 F. and lower, molten sulfur-is suiiciently fluid to be pumped. Between about 340 F. and 446 F. molten sulfur is relatively viscous and ditlicult to pump. If molten sulfur is heated appreciably above 446 F., even up to its boiling point of 832.3 F., or hotter if pressure is applied, the .viscosity 4 isblecreased so that the molten sulfur is once again pumpa e.

In situations where a releasing well is employed to recover a portion of the sulfur, molten sulfur is lifted to the surface through casing 44 having perforations in the lower end thereof and into which lifting gases are pumped through conduit 46. The sulfur in the storage pit may be pumped by pump 48 into the heating vessel 20.

Once the ore strata has been heated so that the sulfur is molten between the heating wells and the adjacent release wells, it is then possible to blow heated, inert gases through the heating well into the sulfur-bearing strata. By including in the hot inert gases a controlled percentage of oxygen and heating the inert gases and oxygen at least as high as the kindling temperature of sulfur, approximately 502 F., controlled amounts of sulfur may-be oxidized. The resulting heat of oxidation is then used to control the temperature of the sulfur in the sulfur-bearing strata so that it readily flows to the bottom ends of the wells for lifting to the surface asproduction product.

The foregoing comprises the basic Yapparatus of this invention. There are, however, other refinements which adapt the apparatus to economic conditions of various localities. For example, if it is desired to use ther heat in the molten sulfur in heating vessel 20 for mining purposes the molten sulfur may be pumped by lpump 32 through line 50 into the casing of the heating well. In this instance, sulfur heated substantially above its melting point may be. used as the mining liquid or as a part of the mining liquid to facilitate the liquefaction and separation of additional sulfur from the gangue `materialsvin the subsurface strata. Further, under conditionswherein the available fuels are expensive or where they impart undesirablecontaminants into the heating liquid such as sulfur, the .sulfur may be cycled through line 5-2 into a burner forY heating the inert gases.

While the Vdrawing illustrates only one gas heating vessel *10,multiples of the vessel 10 may be installed aroundV the heating vessel 20. Such multiples provide a simple method for varying the amount of heat which can be introduced into the heating vessel 20.

In any operation where fixed gases should be kept to a minimum, oxygen can be used in place of air. For example, when sulfur is the fuel, oxygen may be preferred to avoid contamination of the resulting oxidized sulfur gases, which are basic materials to be made into valuable by-products. Alternatively, they may be reverted back to sulfur.

The temperatures of the sulfur in the vessels 20 and 30 may be outside the ranges shown on the drawing without departing from the invention. The temperature ranges shown are illustrative ranges for practicing the invention, and are not intended to be all-inclusive. For example, the lower temperature (325 F.) of the sulfur in the vessel 20 was selected as being an approximate minimum temperature at which it is economically feasible to circulate molten sulfur for heat exchange-particularly when the molten sulfur is utilized as a mining liquid.y Obviously, however, the minimum temperatures of the molten sulfur may be below 325 F. if one so chooses. Similiarly, theV temperature of the molten sulfur in vessel 30 may be above or slightly below the practical range shown on the drawing.

It is not always necessary to have the burner in the heatingrvessel 10pointing vertically down. The burner may be in a horizontal position or it may point vertically upward or at any other angle. The position of the burner depends upon the processing conditions involved. The burner-illustrated is a submerged combustion-type burner which is eminently suitable for heating the gases. Other types of gas burners may also be used. Further, the burner need not necessarily burn gas only.. By variations in construction, the burner can be caused to burn vapors, fluids, dust or solid particles or mixtures of these materials. For instance, in a case where it is advantageous to burn solid particles of sulfur, these particles are conducted to the burner plate through a concentric, annular space designed to conduct sulfur to the burner plate `in proper proportions with the oxidizing agents. The same is true where solid particles of coal such as lignite are used. An example of a rmixture of combustible solids and liquids is lignite particles and catalytic cycle stock from petroleum refinery catalytic cracking. stills which, when admxed with eachother, generate intense heat above the burner plate area as the' mixture emerges upwardly from the vertical conduit.

Combustible liquids such as molten sulfur or a liquid hydrocarbon may be burned in a reaction chamber by spraying or otherwise discharging the combustible liquid into the chamber through a conduit. Support for combustion is provided by supplying air or oxygen to the chamber by an annular conduit surrounding the conduit for the combustible liquid. An ignition wire is provided for igniting the mixture of liquid and air or oxygen as they are discharged into the chamber.

High boiling liquid hydrocarbons such as petroleum stocks is not always burned to completion. A small amount of hydrocarbon not completely burned usually passes on with the gases of combustion. Such hydrocarbon is not desired in the sulfur even in small amounts. For that reason, only liquid hydrocarbons that have been specially prepared and gasiiied prior to burning are used for sulfur recovery from ores. For such products as asphalts, petroleum oils, oil `from shales, most metals, liquid hydrocarbons may be used as fuel. Usually sulfur and fuels with a high sulfur content are not desirable for asphalts, petroleum oils, oil from shales and most metals. Sulfur and sulfur bearing fuels are used only in those instances where sulfur is not injurious to the products involved.

The invention has many advantages in the mining of sulfur and other materials found in subsurface regions and which are capable of being melted, dissolved or modied by a mining liquid or by hot gases and vapors. By means of the invention the cost of mining sulfur is reduced materially because the water does not need to be fresh water; the Water does not have to be specially prepared and treated before heating; there are no boiler tubes required and for that reason tube cleaning is unnecessary. Additionally, the invention makes it possible to mine sulfur and other materials in subsurface regions with greatly reduced quantities of compressed air because the gases of combustion assist in lifting the molten sulfur or other material to be mined from the subsurface regions. The cost of equipment required to practice the invention is much less than that required where stationary boilers are used instead to heat the mining fluid. The space requirements for the apparatus used in the practice of the invention are smaller than the space requirements where stationary boilers are employed to heat the mining uid. The invention is readily applicable therefore to the mining of sulfur by means of apparatus located on barges from sulfur deposits located beneath bodies of water. The operation of the process has the additional advantage that the apparatus can easily be moved from one location to another and is applicable in small units `for the Working of smaller deposits which would not ordinarily be mined by conventional methods because of the high capital investment requirements for equipment.

While the invention has been described largely with reference to the mining of sulfur, the procedures and apparatus herein described may be utilized in the recovery of asphalts and heavy crude oils and other hydrocarbon deposits. The heated mining liquid may be utilized to release more crude oil from petroleum deposits. This is true because the mineral aggregate can be heated suciently to cause expansion of oil occluded in crystalline and other pockets. This expansion breaks open the occluding mineral aggregate jackets so that the oil and gases can be brought to the surface as production products.

The method for heating herein disclosed may also be employed to separate a heat modifiable substance from Igangue materials abovethe earths surface in a manner similar to the mining procedures heretofore described. For example, sulfur is found in pockets vwhere it has been condensed as it rose to the surface after its natural alteration and distillation inthe bowels ofthe earth. For the reason that these scattered pockets are located in mineral aggregate that is too broken andjporous, the sulfur ore is brought to the surface for heating so as to melt and drain olf the sulfur in the ore. Similarly, when molten metal heated substantially above the melting point of the metal mixtures in metal bearing ore is contacted with the metal bearing ore, the metals in the ore melt and, along with the molten metal used lfor introducing heat to the ore, are drained away from the gangue. This method applies for ore either on the surface or for ore beneath the surface. However, very often metal bearing ore bodies beneath the surface are lodged in pockets which are broken and widely separated due to previous shiftings in the earths crust. To cite one example, a site in Arizona contains large quantities of silver-lead ore originally placed in seams and veins. The original placements have been shifted in every direction. Because of this shifting and relocating of the original deposits into a great number of separated pockets, it is impractical to heat the ore in place. For that reason, the ore is brought to the surface for heating so as to melt and drain oi the metals in the ore. Thus, the molten liquid in the vessel 20 may be employed at temperatures substantially above the melting point thereof to melt additional material in an ore-the molten liquid used for introducing heat to the ore and the material in the ore which is liquefied by the heating being drained away from the gangue.

The invention is hereby claimed as follows:

l. A process for mining a substance modied by heat which comprises heating a mining liquid selected from the group consisting of brackish, alkali and salt Waters by direct heat exchange with a heating liquid immiscible with said mining liquid and which has, in turn, been heated in a separate zone by direct heat exchange with hot gases; passing the heated mining liquid into a subsurface region containing the substance to be mined wherein said substance is rendered owable by said heated mining liquid; and lifting said substance to the surface.

2. A process for mining sulfur which comprises heating a mining liquid selected from the group consisting of brackish, alkali and salt water, by direct heat exchange with a heating liquid immiscible with said mining liquid and which has, in turn, been heated in a separate zone by direct heat exchange with hot gases; passing the heated mining liquid into ya subsurface region containing the sulfur to be mined wherein the sulfur is liquied; and lifting the liquied sulfur to the surface.

3. A process for mining sulfur which comprises heating molten sulfur by direct heat exchange with hot gases in a first vessel; removing the gases 'from said first vessel; passing said heated sulfur into a second vessel containing water selected from the group consisting of brackish, alkali and salt waters in contact with said water whereby direct heat exchange is effected between said heated sulfur and water; pumping said Water heated to a temperature above the melting point of sulfur and a portion of said heated sulfur, the latter at a temperature in the range of 235 F.-340 F. or l46-832 F., into a sulfur-bearing subsurface region wherein the sulfur is liquied; and lifting the liquified sulfur to the surface.

4. A method for lreleasing petroleum oil and gases in substerranean strata which comprises heating a mining liquid selected from the group consisting of brackish, alkali and salt waters by direct heat exchange with a heating liquid immiscible with said Water which has, in turn, been heated in a separate zone by direct heat exchange with hot gases; pumping the heated mining liquid into a covering the released petroleum oil.

Refel'euces Cited in the le oifitl'ais `patent UNITED STATES PATENTS 5 A 629,520 Mond July 25, 1899 786,048 Nau Mar. 28, 1905 1,014,573 Davis` Ian. 9, 1912 1,101,790 Doherty June 30, 1914 10 vFrasch Sept.Y 7, 1915 Rockwell Aug. 8, 1916 Knox July 17, 1923 Richardson Aug. 22, 1939 Reed Sept. 12, 1939 Norman Apr. 22, 1952 Miller Aug. 4,- 1953 Folkins Dec. 1, 1953 Heinze July 10, 1956 Warren Oct. 22, 1957

Images