CA1261297A - Electrolytic recovery process and system for obtaining titanium metal from its ore - Google Patents
Electrolytic recovery process and system for obtaining titanium metal from its oreInfo
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- CA1261297A CA1261297A CA000453369A CA453369A CA1261297A CA 1261297 A CA1261297 A CA 1261297A CA 000453369 A CA000453369 A CA 000453369A CA 453369 A CA453369 A CA 453369A CA 1261297 A CA1261297 A CA 1261297A
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Abstract
ELECTROLYTIC RECOVERY SYSTEM
FOR OBTAINING TITANIUM METAL
FROM ITS ORE
ABSTRACT OF THE DISCLOSURE
A process and system, including a single electro-lytic/reaction cell, for extraction of titanium sponge from rutile ore. Magnesium chloride is electrolytically separated into magnesium metal and chlorine gas within the cell. The chlorine gas produced is reacted with rutile ore and coke to produce titanium tetrachloride in a separate chlorinator and the product is directed to the cell subsequent to completion of electrolysis. Titanium tetrachloride is reacted with magnesium metal in the same cell where the magnesium is produced to form titanium sponge and magnesium chloride. The titanium sponge is separated within said cell with the magnesium chloride being recovered and recycled.
Major impurities are separated by distillation. Plural electrolytic cells can be coupled to a single chlorinator in a continuous process. Very pure titanium sponge is produced with this self-replenishing process.
FOR OBTAINING TITANIUM METAL
FROM ITS ORE
ABSTRACT OF THE DISCLOSURE
A process and system, including a single electro-lytic/reaction cell, for extraction of titanium sponge from rutile ore. Magnesium chloride is electrolytically separated into magnesium metal and chlorine gas within the cell. The chlorine gas produced is reacted with rutile ore and coke to produce titanium tetrachloride in a separate chlorinator and the product is directed to the cell subsequent to completion of electrolysis. Titanium tetrachloride is reacted with magnesium metal in the same cell where the magnesium is produced to form titanium sponge and magnesium chloride. The titanium sponge is separated within said cell with the magnesium chloride being recovered and recycled.
Major impurities are separated by distillation. Plural electrolytic cells can be coupled to a single chlorinator in a continuous process. Very pure titanium sponge is produced with this self-replenishing process.
Description
~126i2~7 BACKGROUND OF THE INVENT ION
This invention relates generally to processes for recovering substantially pure titanium metal sponge from rutile ore and more particularly, provides a single vessel self-replenishing electrolytic process and apparatus for obtaining substantially pure titanium metal sponge.
Most titanium metal has been produced rom its ores by the chlorination of its oxide-like rutile ore; the separation and purification of the TiC14 produced;
the reduction of the TiC14 to titanium metal by use of an active metal such as magnesium, sodium or calcium and electrolytically recovering the reducing metal and chlorine, both for recycling.
Another well ~nown reduction process for obtaining titanium metal from its ore i8 the K~oll process represented by U.S. Patent 2,205,854.
The Kroll process involves the reaction of the titanium tetrachloride with molten magnesium metal in an inert gas atmosphere at normal or atmospheric pressure. A refractory metal is employed as a lining for the steel reaction vessel or crucible, the refractory metal being oxidized to prevent diffusion of the lining into the steel. The magnesium metal is heated to 800C and titanium tetrachloride dripped onto the metal. The product i8 solid titanium metal and liquid magnesium chloride. Separation of the metal requires further tedious and expensive processing.
This invention relates generally to processes for recovering substantially pure titanium metal sponge from rutile ore and more particularly, provides a single vessel self-replenishing electrolytic process and apparatus for obtaining substantially pure titanium metal sponge.
Most titanium metal has been produced rom its ores by the chlorination of its oxide-like rutile ore; the separation and purification of the TiC14 produced;
the reduction of the TiC14 to titanium metal by use of an active metal such as magnesium, sodium or calcium and electrolytically recovering the reducing metal and chlorine, both for recycling.
Another well ~nown reduction process for obtaining titanium metal from its ore i8 the K~oll process represented by U.S. Patent 2,205,854.
The Kroll process involves the reaction of the titanium tetrachloride with molten magnesium metal in an inert gas atmosphere at normal or atmospheric pressure. A refractory metal is employed as a lining for the steel reaction vessel or crucible, the refractory metal being oxidized to prevent diffusion of the lining into the steel. The magnesium metal is heated to 800C and titanium tetrachloride dripped onto the metal. The product i8 solid titanium metal and liquid magnesium chloride. Separation of the metal requires further tedious and expensive processing.
- 2 ~
6~2~37 Winter, U.S. Patent No. 2,890,112 discloses another method for producing titanium metal by reduc~ion of the tetrachloride wherein both the magnesium and chlorine are recovered and recycled. winter suggests the use of sodium metal produced by electrolysis of a ternary salt along with a molten reaction calcium-magnesium alloy and chlorine gas. The chlorine gas is reacted with a tltanium ore/coke mixture. The reduction does not employ magnesium alone. A process involving molten sodium o~ten is dangerous and expensive.
Glasser et al, U.S~ Patent No. 2,618,549 provides a method ~or production of elemental titanium ~rom its ores by reductlon of a titanium halide such a8 titanium tetrachloride by means of an alkali metal amalgam such as is produced in mercury-amalgam chlorine cells used in the production of caustic ~oda. Chlorine produced in the electrolysis 18 employed to produce the titanium tetrachloride from the oxide ore.
The amalgam reactant is separated after lts productlon and added to a reaction vessel along with the titanium tetrachlorlde. The reduction reaction i~ carried out in the presence of an inert gas and with vigorous agitation of the reactants. When the reaction is completed, the product is transferred to a separating furnace without expo~ure to air using gravity or other feed means. The product is first distilled to drive of~ mercury and thereafter, the residual material is heated to above 1500F to separate sodium chloride. Subsequent purlflcation steps are suggested. Not only does the Glasser ~2~Z9~
process require the use of inherently dangerous mercury and sodium, it is expensive, requires much equipment and multiple steps as well as proximity and access to caustic soda processing plants.
Other processes are described in U.S. Patents to Maddex, 2,556,763; Blue, 2,567,838; Winter, Jr., 2,586,134; winter, Jr., 2,607,674S Winter, Jr., 2,621,121; Loonam, 2,694,653 and Dietz, 2,812,250.
Thus it is noted that the process of obtaining titanium metal from rutile ore by reduction thereof i8 well known. The conversion of the ore, which is in the form of an oxide, to the tetrachloride and reaction of the tetrachloride with magnesium metal to form magnesium chloride and titanium metal has been discussed. Titanium produced in this manner required considerable purification, both from impurities originating from the ore as well as removal of magnesium chloride trapped within the product and any remaining magnesium metal. Known processes often lncluded electrolytic processes where the production of magnesium metal was electrolytic. Magnesium was produced electrolytically isolated, removed from the cell and purified.
The purified magnesium metal then was remelted for the reduction reaction with the titanium tetrachloride. These processes were unduly expensive in terms of the energy requirements, the precautionary expedients required for safety (especially in view of the reactivity of magnesium and the need to separate and transfer 8ame), the number of steps and cost of purification, the waste of raw materials and loss in both transfer and purification.
~26~29'7 Of all the problems inherent in the conventional processes for reduction of titanium ore with magnesium metal, exposure of the magnesium metal to air was the most serious, particularly in terms of safety.
Conventionally, processes for producing titanium sponge include draining of the magnesium chloride from the reaction cell as the reduction reaction proceeds. The drained magnesium chloride is recycled by electrolysis producing magneslum metal, which is drawn from the cell and cast as ingots. These ingots then are placed in a steel retort and melted. The resulting molten magnesium is either transferred to another vessel for reaction with titanium tetrachloride or the molten magnesium charge reacted in the same vessel in which it was melted.
The reduction reaction of titanium tetrachloride with magnesium is exothermic, ~ith the by-product,magnesium chloride,heated to about 1400F. Thus the magnesium chloride i5 molten. Conventionally, the heat released in the exothermic reaction is lost, that is, not advantageously used.
Another problem encountered with conventional processes is the establishment of access both to the titanium metal produced, and to the magnesium chloride by-product. The reaction vessel conventionally has to be cooled. After cooling, operators using physical means such as jack-hammers or the like must literally break up the soldified material. The titanium metal resulting must be reined for obtaining the purity commercially desired. A
further danger encountered is the production of harmful amounts of phosgene gas resulting from the reaction of impurities in the ore with chlorine produced, or with the i26~297 magnesium chloride, under the elevated temperatures of the reactions.
The production of titanium metal i5 a very precise operation since the hot metal combine~ with oxygen, S n~trogen and moisture of the air. The metal also combine3 with carbon and most construction metals. ~efractory materials al~o are vulnerable to attack due to their oxygen content. Conkaminants produced render the resulting metal ~o hard and brittlo that it is useles~ for most application~. ~n~e 6uc~ co~taminant5 are picked up, there are no practical methods availa~le ~or removing such impuritie~. If one carries out the reaction under an atmosphere of an inert gas such as helium or argon at around 800C, the titanium alloys with the iron in the lS vessel to a minlmal extent. Neverthele~s, the metal layer in contact with the ve~sel wall aontain~ too much ixon to meet speci~iaation~ and must be disGarded.
In operation under conventional processe~, the magnesium ingots are picXled in dilute acid to remove surface oxidation ~ollowed by rinsing an~ drying steps.
~he dried magnesium charge i~ placed ln a cylindrical ~lat-bottomed steel pot. The oover i8 welded in place, the vessel te~ted for leaks and, if no lsaks are detected, all the air is removed from the ves~el by evacuation, followed by rele~se of the vacuum repeatedly with helium or a~on. The ve~el, ~ith the mAgnesium charge, is placed in 8 vertical aylindrical furnace ~nd heated either by ele¢tricity or Sy ~uol combustion. As soon a~
the magnesium ~egins to melt, purified titanium tetrachloride is ~ntroduced at a care~ully controlled rate.
J~
12~1~9'7 Inert g~s pressure within the vessel ~5 maintained to prevent lnward air leakage. The rate of lntroduction of the titanium tetrachlorlde i~ controlled such that excess heat generated in the vessel is dissipated through the veRsel walls, external heat being unnecessary to maintain the vessel temperature between 750 and 1000C.
Accordingly, improvements are sought in the recovery and in the purification of the recovered product with reduction in the danger, lowering of the costs, especially energy cost~, in¢rease in product purity and acce~ to the desired product.
The lesser handling the better and the lesser exposure o~ the reactants are important crlteria to be met.
126~Zg7 SUMMARY OF THE INVENTION
A system, including a single electrolytic/reaction cell,for obtaining titanium metal sponge from rutile ore ~y -c~nye~ting the rut~le,ore to titanium tetrac~loride in a separ-ate ves~el'and ~eeding the't~tanl`'um tetracfiloride to a combined electrolysis/reaction cell containing molten magnesium metal produced by electrolysis of magnesium chloride in that cell and reducing the titanium tetrachloride with the molten magnesium to produce titanium sponge and chlorine, diverting the produced chlorine to that vessel in which the titan$um tetrachloride is produced and the molten magnesium chloride produced by the reduction reaction is retained for subsequent electrolysis in the same cell.
Impurities in the ore are distilled from the reaction vessel in which the titanium tetrachloride is produced. Impurities in the titanium sponge are distilled therefrom.
~261;297 BRIEF DESCRIPTIO~ OF THE DRAWINGS:
FIGURE l is a diagramm~tic chart showing the chemical reactions involved with the system according to the invention and the relationship of the reactants and products thereof;
FIGURE 2 is a flow diagram illustrating the system of obtaining titanium metal sponge of high purity from rutile ore according to the invention;
FIGURES 3 A, B, C and D are graphic representationas illustrating the 8tages in the process accordin~ to the invention;
FIGURES 4 A, B and C are diagrammatic elèvational views in section illustratlng the combined electrolytic/reaction cell in the respective stages of the system a~ shown in FIGURES 3 A, B, C and D;
FIGURE 5 is a diagrammatic representation of one system according to the invention for obtaining titanium metal sponge;, FIGURE 6 i8 a diagrammatic representation similar to that of F~GURE 5 but illustrating a modified system;
FIGURE 7 is a diagrammatic elevational sectional representation of a chlorinator as employed in the systems of FIGURES 5 and 6;
~6~97 FIGURE 8 is a diagrammatic elevational sectional representation of a modified electrolytic/reaction cell according to the invention, and FIGURE 9 is a diagrammatic elevational representation in section of a further modified electrolytic/reaction cell according to the invention.
1~1297 DESCRIPTION OF PREFERRED EMBODIMENTS
.
As was noted hereinabove, the invention herein concerns a new and improved closed system for obtaining substantially pure titanium metal from its naturally abundant ores, such as Rutile ore. The system, and particularly the improved apparatus incorporated in said system, enables the production of titanium metal sponge of high purity with little loss of reactants empioyed and high efficiency of operation in its minimization of the use o energy, the invention being particularly characterized by the electrolyBi8 and t~ ~eductlon steps being performed in a single vessel.
The basis chemical reactions employed in the ~ystem according to the invention are as illustrated in FIGURE 1, the arrows therein illustrating the generation and recycling linkages.
Basically, magnesium chloride is electrolyzed to produce magnesium,which i8 employed as the reducing sgent reacted with a titanium halide and chlorine gas.
The chlorine gas iB employed as a reactant with titanium ore and coke to form titanium tetrachloride, the reactive halide to be reduced by the magnesium formed by electrolysis above mentioned. One typical composition of Rutile Ore that is representative is set out in the following ~able I.
TABLE I
RUTILE ORE
Australian TYPICAL CHEMICAL ANALYSIS
Tio 96.80% Guaranteed 2 95% Minimum Fe203 0.65 Zr2 0.96 SiO2 0.65 Cr203 0.18 V25 0.51 S 0.01 A123 0.22 CaO b.Ol MgO 0.06 PbO 0.06 Ignition Loss 0.15 T ~
Plus 52 Mesh 0.3 " 72 " 9.5 " 100 " 55,9 " 150 " 30.9 " 200 " 3.1 Pan Granular, 200 mesh, 325 mesh and 400 mesh available from Cincinnati in ~ags. Granular also available in bulk.
~.~61;~97 A mixture of coke (source of carbon) and said Rutile titanium ore is introduced into a vessel hereinafter referred to as a chlorinator, to which is added the chlorine gas produced during the electrolysis of magnesium chloride.
The magnesium produced in the electrolysis process is retained in the single electrolytic/reaction cell while the reaction between chlorine and the rutile ore/coke mixture takes place in the chlorinator. The product of chlorination, titanium tetrachloride, is returned to the electrolytic/reaction cell and reacted with the magnesium 80 a~ to produce titanium metal in sponge form and to replenish the supply of magnesium chloride in said electrolytic/reaction cell.
The temperature of the reaction is controlled to maintain a level sufficient to vaporize, for discharge, any impurities such as magne~ium metal, magnesiu~ oxide, trace elements, etc. which may have remained subsequent to the reduction reaction. Separate distillation may follow, The major purification of the Rutile Ore occurs during the chlorination process, where the trace elements, including iron, silicon zirconium, aluminum, vanadium and others, mostly as oxides, are converted to their respective chlorides and are discharged from the chlorinator along with titanium tetrachloride. The discharged titanium chloride is di~tilled for purification purposes prior to entry into the electrolytic/reaction cell for reaction with the magnesium, said magnesium ~eing retained within the electrolytic/reaction cell in which it i8 produced.
Referring to FIGURES 3 A, B, C and D as well as 4 A, B and C, there are illustrated electrolytic/reaction cells which characterize the invention herein as shown in the stages of ... . . . . . . ... . .. ... . .. .. . . . .. .........
æ~ 7 the process. The electrolytic/reaction cell generally is designated b~ reference character 10 and comprises a steel cylindrical vessel or retort having a removable upper section 12 and a lower section 14. A steel open-topped product container 16 i8 disposed within the lower section 14.
Container 16 i8 provided with a bottom or floor 18 and has plural drain openings 20 formed in the wall thereof closely adjacent to the floor 18.
Heating elements 22 are provided about the lower section 14. The upper section 12 of the cell 10 has a circum~erential flange 24 adapted to be seated sealably ~ecured to a like flange 26 on the lower section 14. The upper section 12 is fitted with a cover 28 sealably coupled thereto. Cover 28 has an axial passage 30 through which an elongate ceramic tube 32 is ~itted. The tube 32 is selected of a length whereby it extends into the open top of the Or~
container 16~hY~ht~ a sheath for the passage of the graphite rod 34 functioning as ~he anode.
The anode 34 extends upwa~dly through the cover 28 and out of cap 36 ~ealably secured o~to said cover 28 b~t insulated electrically therefrom by in~ulator 38. The cathode i~ container 16. The cap 36 has an outlet port 40 which is capable of ~eing coupled to conduits leading to the chlorinator ~to be described). Lifting rods 42 and 44 are passed through the cover 28 by way of seal me~bers 46. The li~ting rods 42 and 4-4 are coupled by weldiny or otherwise to the rim o~ container 16 for li~ting same into the section 12 when desired in the process, as shown in FIGURE 4C.
As shown in FIGURE 3A where the electrolytic/reaction cell 10 is in a condition shown in FIGURE 4A, a load of lZ~ 7 magnesium chloride is added to the lower section 14 of the cell 10. The section 14 is heated to about 1350F
to melt the magnesium chloride. The level of the liquid magnesium chloride is brought to a level L-l in the container 16. The upper section 12 with the associated anode 34 is seated onto the lower section 14 and bolted in place. A D.C. voltage at high amperage is supplied between the graphite anode 34 and the steel container 16 and the molten magnesium chloride is subjected to electrolysis to produce chlorine deposited at the anode 34 and magnesium metal. The chlorine gas is trapped within the tube 32 which surrounds said electrode 34 and is discharged by way of said port 40 to conduit means leading to the chlorinator.
The magnesium metal produced during the electroly~is proces~ deposits on the surface of the conta~ner 16 ~cathode)and rises upwaxd through the molten magnesium chloride toward the ~urface thereof. The tube 32 which vent~ the chlorine gas further serves as an electrical ln~ulator to prevent the magnesium metal, represented by reference character 48, which will float on the surface of the magnesium chloride, from short circuiting the electrolytic/reaction cell 10.
In the first cycle of operation, the electrolytic/
reaction cell 10 functions as an electrolytic cell for produc-tion of the magnesium metal which is used as the reducing agent, and the chlorine gas for delivery to the chlorinator. At a current efficiency of about 80~, approximately 8 kilowatt hours of power is required to produce one pound of magnesium.
The same amount of power,of course,produces three pounds of 12~12~'7 chlorine gas which leaves the cell 10.
FIGURES 3 (A, B, C and D) illustrate diagrammatically the stages of the process while the representations of FIGURES 4A, 4B and 4C illustrate the condition of the cell 10 at those stages respectively. FIGURES 3A and 4A
diagrammatically illustrate the cell 10 at the initial staye o~ the process just prior to the initiation of the electrolysls procedure. The first cycle consists of the electrolysis and the level L-l of the molten magnesium chloride i8 represented. At the end of the first cycle, the total liquid level L-2 iB lower than the level L-l at the start of the electrGlysis. This change in level results from the 1088 of three pounds of chlorine leaving the cell 10 for ~ach pound of magnesium produced. Particular attention thu~ is directed to FIGURE 3B illustrating the floating magnes~um metal 48 upon magnesium chloride remaining in the containex 16.
The second stage or cycle in the process is initiat-ed when there is sufficlent floating magnesium metal to reach the bottom of the refractory tube 32 illustrated in Figure 4A.
At this time, the anode 34 is withdrawn along with its surrounding refractory tube 32. If plural electroylsis/
reaction cells 10 are employed, the assembly o the anode 34 and its surrounding tube 32 is installed in a second 2S electrolysis/reaction cell and electrolysis initiated within that second cell 10. As illustrated in Figure 4B, a feed system 50 including valve 52 and piping 54 is coupled to the upper section 12 of cell 10 in substitution for the electrode assembly just removed. The feed system 50 links the supply of ,.. ,. ~,,. ~ ,"
titanium tetrachlorlde to said section 12 of cell 10.
The valve 52 i8 opened and titanium tetxachloride is introduced into the cell 10 to drop upon the open bed of floating magne~ium metal in the container 16. An inert gas, ~uch as argon from a source 56 thereof may be employed as a flushant during the feeding process by which titanium tetrachloride i8 introduced. Titanium metal i8 produced by reaction with the magnesium metal a8 shown in FIGURE 3C, the cell 10 ~eing illu3trated in thls reduction reaction stage in FIGURE 4B. Thu~, a~ter the reduction xeaction i8 completed, by which titanium metal and magnesium chloride i8 produced, the third stage or cycle is initiated, ~low o~ titanium tetrachloride being terminated. For each pound of magnesium metal in the cell 10 at the start of the sscond cycle, ~our pound~ of titanium tetrachloride i8 added to produce one pound of tltanium and ~our pounds o~ magnesium chLoride. The greater amount o~ the magnesium chloride remainlng at the end o~
the xeduction reaction ~loats upon the body of titanium metal ~pxoduced in ~ponge ~orm). Upon completion o~ said reduction reaction, the container 16 i8 raised within the lower section 14 to the upper ~ection 12 o~ cell 10 without exposing the a8ll interior to ~ir, to enable driinage of the magnesium chloride and cooling o~ the remaining body primarily of titanium metal sponge.
Once the titanium metal has cooled at least below 800F and pre~erAbly reached a temperature in the vicin~ty o~ 600F, tho cell 10 can be openod. ~he container 16 with its primarily titanium content can be removed. The titanium metal is not reactive at such temperature and hence the container 16 and the titanlum metal therein can be removed bodily and placed within a vacuum chamber (not ~hown) and heated to 1850F to boil off any entrapped magnesium chloride, as well a~ any remaining magnesium metal or magnesium oxide that may have ~een entrapped therewithin. Conventlonal cold traps ~not shown) may be provided for coupling to the vacuum chamber for receipt and condensation of the gaseous magnesium chloride, magnesium metal and magnesium oxide fraction~ for recovery and recycling back to the pxocess.
The chloxinator i~ illustrated in FIGURE 7 wherein the chlorine produced in the cell lO by electrolysis of chloride i~ recycled to prepare titanium tetra~hloride. The chlorinator, designated generally by r~ference 60, operates at about 1650~ and is raised to such temp~rature externally, S as by the furnace 62 surrounding same. Onae the react~on, ~i2 ~ 2 C ~ 2 C12 ~ iC14 ~ 2 CO ~ ~
i~ initiated, no further ~xternal heat i8 re~uired ~inca the said xeaction i8 exothermic. Either pressure transfer ~ystem 64 or a gravity transfer system 66 iB coupled to the chlorinator 60 to trans~er the titaniu~ tetrachloride produced therein to a speci~ic location ~or introduction to the cell 10.
rn Pre~g$ 5 the gra~i`ty trans~r ~yste~ 64 for the titanium tetrachloride i8 illustrated wn~le FIGURE 6 illustrates a pre~sure t~ansfer sys~em 66 ~ub~t$tuted in the system. The gravity trans~r ~y~tem 64 18 simpler th~n the pressure transfer ~ystem, containing many more valve~ and containers.
Howev~r, where the sites o~ in~tallation have relatively low roof8, there is a he~ght limitation maXing use of a pressure trans~er system imperatlve.
~L261297 Referring to FIGURE 5, a xepre8entation of an exemplary system i~ provided wherein the',re are a pair of cells lG and 10' used alternatively. Cell 10 ha~ just completed the electrolysis of magnesium chloride and contain~ two pounds of magnesium in it3 product container.
Cell 10' is at ready, with the magnesium chloride therein molten. At the moment electrolysis was completed in cell 10, power i8 switched from coll 10 to lO' to initiate electroly~is theroin.
~e~err~ng al~c to FIGU~ES 5, 6 and 7, $11ustrating more details o~ the ~ystcm, including chlorlnator~ 60 and 60', the titanlum cre i~ mixod with car~on ~n the ~orm o~ coke in mixer/~eed ~opper 74 and directed t~rough a feed sy~tem 76 including valves 78 and 80 to the inlet 81 at the top o~ the chlorinator 6~. L~ne~ 82 and 84~, carry the titanium tetrachloride proauce~ in the chlorinator 60 respectively to a receiving tan~ 86 via valve 88 and line 90 or to a purifie~ such as a distillation'still 68 via valve 92 and line 94. The line 94 snter8 the storage/feed tank 85 at inlet 98. The tank 86 is vented by way of line 100 via valves 102 to dry~r 104 which includes a bed of calcium chloride. Valve 106 controls passage through lines 108 and 110 to an exhaust 112 which may include a scrubber to prevent undesirable components ~rom esoaping to the atmosphere.
The purifier or still 68 is illustrated positioned intermediate the chlorinator 60 and the cell 10. Although a more pure titanium tetrachloride can be produced u~ing the ~till 68, th~ di~tillation step ~er~ormed thereby mav not be needed.
In the chlorinator 60, th~ ferric oxide is converted to ferric chloride, wh$ch is nonsolubl~ in titanium ; ,, ~26~2~7 tetrachloride and remains as a brown solid in the bottom of the titanium tetrachloride container. Zirconium oxide is converted to zirconium tetrachloride, same being a white solid which deposits on the condensor tubes of the still and/or on the wall 70 of the titanium tetrachloride storage container 86.
The zirconium tetrachloride does tend to clog the ~ystem and must be cleaned out periodically. Since zlrconium tetrachloride is soluble in water, periodic flushing with water will remove ~ame. The silicon ~ioxide in the ore is converted to silicon tetrachloride, which melt~ at -70C. and boils at 57C. Silicon tetrachloride and titanium tetrachloride are fully soluble in each other and hence the silicon in the ore will be carried over into the titanium metal produced, unless remedial action is taken.
Titanium tetrachloride boils at 136C while the boiling poi,nt of silicon tetrachloride is 57C. The container 8-6 for storing titanlum tetrachloride should be maintained above 57C, preferably at 70C. Under such temperature condition, the silicon tetrachloride produced in the chlorinator 60 will not condense in the titanium tetrachloride chamber container but will continue to and through the exhaust system. Vanadium oxide in the ore 25 i8 converted to vanadium tetrachloride (boiling at 152C) and is carried over into the ti~anium produced. Vanadium i~ not an ob~ectionable impurity and hence even if vanadium is carried over into the titanium product, it i~ not a serious problem.
1~612~
In FIGURE 6 the same basic system components as in FIGURE 5 are provided but the ~y~tem i~ pressurized and the feed from the chlorinator 60.to the titanium tetrachloride sterage tank 86'is a pressurized feed. The chlorinator 60~is supported on support structure 114 at ground level, with still 68' seated at ground level.
The titanium tetrachloride produced in the chlorinator 60' i~ pumped upwaxds to the storage tank 86' from the chlorinator 60~bY way of the still 68' and from there, to the ~to~age tank 86' located substantially above the electrolysi~/reaction ves~el or cell 10.
Looking at FIGURE 7, the chlorinator 60' comprise~ an inner core 116 formed o refractory tubing seated ln through pas~age 118 formed in surrounding electric furnace~ 62 and extending outward from the top 120 and floor 122 of said furnace 62 through a passage 124 formed in support 114. ~he opposite end~ of the core 116 are capped and ~ealed by upper cap 126 and lower cap 128.
Lower cap 128 includes the chlorine in~ection system 130, including an in~ector 132 having an outlet 134 and an inlet 136 extending outward of the cap 128. Inlet 136 i8 coupled into line 140 leading from the electrolysi~/reaction cell 10.
The upper cap 126 accommodates a pair of outlet ports 140 and piping 142, and a centrally locatod inlet port 144- Note that re~erence numeral 143 indicates the equivalent to lines 82 and 84 in FIGURE 5. One of the outlet pipo~ 142 1- ¢oupled through fail-safo pneum~tic ball valve 146 to line 94 loading to the ~till lnlet 150.
outlet line 152 extending ~rom t~e ~icin~ty of th.e floor of the ~till 68' is directed to ~he ~ece~vi~g tank 86 ~h~le :1261297 line 154 i~ directed to the scrubber/exhau~t 112'. The chlorinator 6o~8 illustrated as installQd in the pres~ure feed system of FIGURE 6. An intermediate ~econd still 15 can be interposed in ~he line 152 leading to the storage tanks 86 or 86' from which titanium tetrachloride i~ fed to the electrolysis/reaction cell 10.
The ore/coke feed system 76 preferably is a gravity/mechanically augmented system and comprises a cylindrical mixer/hopper 74 positioned with it~ outlet above inclined r~mp or belt arrangement 156 leaaing to the inlet 158 of chute 160, the outlet 162 of which is positioned to fQed tube inlet 164. Electrical vibrator~ 166 and 168 are arrange~ operatlve upon the belt arrangement 156 and upon the upper portion of ~eed tube 164 to assure continuity of lS feed of the orQ/coke mixture. The feed tube is formed of sections 170 and 172 coupled together and includes the pair of valves 78 and 80 whlch can be describe~ as ~ail-safe valves.
The ~ottom section 174 tQrminatQs at 81 interior of the upper end of the r~fractory (cer~mic) tube 116 o~ the chlorinator 60'.
Tho metho~ o~ feeding the Rutile ore/coke mixture to th~ chlorinator is simllar to the method of feeding the titanium tetrachloride to the Qlectrolysis/reaction vessel, although a very flowable sand-liXe mixture is treated.
The conventional ball valve used to control feeds cannot close well enough when ~ull of such sand-like mixture. Accordingly, vibrator 166 operates to ~ill a section 170 of the feed pipe above the ball vAlves. ~his section 170, a~ shown, cannot be over-filled. It has a volume which is less than the volume in the pipe sQction between the two valvQs, 78 and 80.
Once this upper section 170 of the feed pipe is filled, ~ . ~
~261297 material overflows to ramp 176 and activates an overflow detector 178 which stops the feeding mechanism. ~alve 78 then opens and drops the unit charge into the pipe , section 170 between valve~ 78 and 80. Valve 78 then closes and vaive 80 opens and drops the charge into the chlorinator 60' below ~y way of the remaining pipe 173. By allowing ~or the upper pipe section 170 to have a volume less than the volume between the two valves, a valve i8 never required to close when filled with the ore/coke mix. Of course, the feed rate is governed by the volumes of the pipe and the cy¢le rate. Over~lo,w collector 180 receive~ the ore/coke mixture overflow from ramp 176 and directs same back to hopper 74 via line 182.
Two modified embodiments of the invention are illustrated in FIGURES 8 and 9. ,These cell embodiments 10" and la'"1 differ from the earlier apparatus primarily in that the positions o~ the cathode and,anode have been rever~ed, the tubular anode now belng the outer tubular shell of the cell formea by a graphite crucible 184. This,electrode mu~t be fo~med by a machining proce~ from electrode grade graphite rather than a~ ordinary graphite crucibles (which are formed primarily of clay graphite).
One here exchanges the relativé positions o~ the anode and the cathode in the electrolysis/reaction cell 10 25 80 that completion of the electrolysis process i~ permitted with the reduction reaction producing titanium then'not only proceeding within the same ves~el but without changing top~ on the cell. With this arra,ngement, there is less opportunity ~or air to enter the system. Accordingly, the titanium thus produced will have lower oxygen content.
ix; ~: .
,................... ~
~26~
The bottom 186 of the graphite crucible 184 is covered with a disc 188 of refractory material simultaneously functioning as an electric insulator and to prevent the ~ormation of chlorine gas along the bottom 186. Chlorine is ~o~med along the sides of the graphite crucible 184 (the anode) and rises to the surface o~ the molten magnesium chloride, ex~ting through the top 190, as shown. Magne~ium is released at the cathode, floats as a li~uid body to the surface and i5 contained within the tube 214.
lQ Heaters 192 are provided for heating the outer surface of the crucible 184. Thermocouple 194 is provided for monitoring the temperature.
Magnesium chloride is heated by heaters 192 provided on the outer surface of the graphite crucible 184, with the addition o~ magnesium chloride continuing until the cell is ~illed to a level corresponding to ~-1 in FIGURE 3A.
For electrolysis a 7 ~olt D.C. voltage at 30Q~ Amps is directed from a source to the cell lQ to initiate the electrolysis. During the electrolysis process, chlorine gas is formed and deposited at the anode and leayes the cell, with the level within the cell being reduced to a level corresponding to L-2 in FIGURE 3B. At this point in the process, most o~ the liquid in the container196 is magnesium while all the liquid exterior of the product container i8 magne-sium chloride. Some liqu~d in container196 also will include some magnesium chloride since the container has openings in it which permit free passage of magnesium chloride through the container bottom. The li~uid magnesium floats on top of the magnesium chlor de. The electrolysis continues until a predetermined amount of the magnesium is produced. The level L-2 shown in FIGURE 3B represents containment of about ~6~2~7 two pounds of magnes~um metal. In order to produce four pounds of magnesium, one would start with a level L2 about twice as high as represented in level L-2 in FIGURE 3B.
Current requirements would ~e doubled, to 6000 Amps. The process ~ 24a -lX6~297 would take about one hour to produce about four pounds of the reducing agent, magnesiu~. The conta~iner 196 is equivalen~
to the container 16 of Figure 4 in function but inc~de~ a perforate bottom 198 to which a depending cylinder 200 is :
secured, as by welding. Cylinder 2Q0 is provided with drain passages 202. The ~e 214 is covered with disc 204 carrying elongate vertical tube 206, electrical connection being made thereto at 208.
The cell section 14' i8 Eormed by joining a pair of pipes 210,212 together defining a sheath for tube 214. ~ube 214 has a cap 216 through which tube 206 passes.
The feed system 76 is coupled to the upper end of tube 206. Tube 206 serves as the ca~hode an~ as a cohduit for feeding titanium tetrachloride to the magnesium once electrolysi~ is complete. The magnesium chloride formed during the reduction reaction i8 drained through perforate bot~om 198 and drain passages 202 remaining in ths crucible 184.
Tube 206 is weldably secured to perforate container cap 207.
The lower section 12' of cell 10" carries a cap 218 bolted to flange 220 by spring biased bolts 222.
The upper end o~ crucible 184 is secured in engagement with the cap 218 and electrical connection is made via the cap 218 by connector 224.
Once the reduction reaction is complete, the container 196 is raised within tube 214 for draining any magnesium chloride from the container 196.
In FIGURE 9 there i8 illustrated a ~urther modified embodiment of the invention generally designated by reference character 10"' and is similar to cell 10"
except that the anode comprises a graphite tube 226 positioned ;"
~126i297 to replace the graphite cruci~le 184 wh~ch functioned as tho anode in the embod~-ment illustrated ln FIGVRE 8.
The tube 226 i~ seated in a refractory bed 228.
The cathode is formed as a cylindrical rod 230 5 located secured to the floor 232 of the lower sect~on 14"
with an axial interior Calrod heating element 234. Electrical connection 236 i8 made to a heavy copper bu88 bar 238.
The ~owex input i8 coupled to one of the ~lange bolts 242 with the cover 244 being insulated electrically ~rom tho cell 10"'. A ~econd the~mocouple 246~may be introduce~ to the container 196'. ~ube 206 may be threadably connected to cap 207'. Otherwlse, the constructions of the eloct~oly~is/reactlon cells are similar.
In both FIGURES 5 and 6 the systems illustrated contain two reaction cells connocted to one chlorlnator 60 ox 60'. Throo r~action cells can bo grouped ~round one chls~nator at 120 spacing. ~wo of the cells could be cycled while tho th~r~ i8 down for maintonance, i.e., cleaning, ~tc.
By this mothod, a continuous process 18 obtalned, One ~ower ~upply ~8 noede~, and thls su~ply operates continuously, ~roduc~ng magnes~um and chlo~ine. ~he protuatlon o~ titanium in a cell would continuo until the product container i8 rea~onably full. Tho production rate of tho system iB govexned by the amount of power supplisd to it.
~he titanium sponge 18 purlfiod of any adhor~ng ~gC12 and magnesium metal by the conventional method o~ heat~ng to 1750-1800 in a vacuum. At this temperaturo ~n a vacuum, both MgC12 and m2gnesium boil o~f. They are rocovered and added back to the cells, as discussed earlier.
All valves employéd in the system o~ FIGURES 5 and 6 are of the pneumat~c, fail-safe des~gn. T~e valves open ~Trade Mark - 26 -with air pressure and are closed with a spring. Thus, if air pressure or electricity fail, the valves close. The valves are of all stainless steel parts with Teflon* seals. This type of valve has been found to be satisfactory to handle titanium tetrachloride (TiC14) as a liquid or a gas, and is also suitable for chlorine gas.
Looking back at FIGURES 5 and 6, the cell 10' is shown after completion of the electrolysis cycle and during a flush cycle prior to the introduction of TiC14. At the end of the flush cycle, valve 250 and valve 252 will close. All other valves will remain as described. To introduce the TiC14, first valve 250 is opened for a short period. This allows Ti-14 to ~ill the pipe section 254 between valve 250 and valve 252. Then valve 250 is closed. With valve 250 closed, valve 252 is opened. This allows the TiC14 between the two valves to drop into the cell below and thus onto the surface of the molten magnesium. The TiC14 reacts with the magnesium. Valve 252 then is closed. Valve 250 again is opened for a short period and then closed to allow the section of pipe between the two valves to fill with TiC14 again. Once valve 250 closes (a~ain), valve 252 may be opened to allow another charge of TiC14 to enter the cell below. Thus TiC14 may be added to the cell below at a controlled rate. The rate is determined by the volume of the pipe section between valves 250 and valve 252, and by the rate at which the valves are cycled. To determine a reasonable rate to feed the titanium tetrachloride (TiC14), thermocouple 246' is enclosed and monitored. The temperature within the lower section of the cell 10, 10', 10" and 10"' should be kept below 1500F.
~Trade Mark 126~2~
In the event of a malfunction in the cycling of valves 250 and 252, causing both'valves to be open at the same time, then the cell 10 below would explode. For this reason, the cell cover 244 is held on by spring biased S bolts 242. This method of securement serves two functions:
(1) A pressure buildup within the cell 10 will raise the' entire head to relieve such pressure. Thus the spring hold-down 242 acts as a safety valve; (2) the spring hold down 24Z also acts to assure good electrical contact between the cell top 244 and the graphite crucible 184 inside, Wlthout this spring pressure, the outer steel shell of the cell 10" and 10"' would expand in length dur~ng heatup. This increase in length would lead to poor contact between the cell top 244 and graphite crucible 184.
S$nce the system must carry 6000 amps, good contact must be maintained.
An expansion chamber 258 is provided with valve 260, Valve 260 remains open while titanium tetrachioride is belng added to the'cell 10" or 10"'. Its function is to e~ualize pressure between the area above the molten magne~ium within the container 16 and the area above the molten magnesium chloride ln the graphite crucible 184.
When a unit charge of titanium tetrachloride is dropped from valve 252 on the surface of the molten magnesium, there is a pressure ~urge. Of course, much happens in a very short time durlng this part of the cycle. First, the titanium tetrachloride changes state from li~uid to gas due to the high temperature, but at the same time, it i~
reacting (either as a liquid or a gas) to form solid ,. . . . . . .. .. . .... _,. __ 1~6~
titanium sponge, and li~uid magnesium chloride. One observes a sharp pressure surge rapidly decreasing to normal, a~d an increase in the bath temperature. The pressure surge could cau~e a problem within the cell. I~
S not compensated fox by connecting the innex and outer sect~ons of the cell with valve 260 the pres~ure surge could force the level of magnesium down in the container 16 Thls would force some of the magnesium out through the bottom of the container 16 ~nd into the outer cell chambe~. Magnesium thu~ ~orced out would be lost to the process. It would be recovered, however, when the cell i~ operated electroly~ically, since the chlorine produced would react with it to form magnesium chloride. ~hus the cell would "clean" ltself in the event this occurred.
The ~arge volum~ expansion chamber 258 helps dampen the pxe~sure surg~. One addit~onal feature has been incoxporated to help h~ndle n pxessure surge, if such a surge bacomes a problem. The refraatoxy tube ¢an be lowered from the po3ition shown in ~IGURES a ox g to the bottom o~ the cell. This can be done prior to the addition o~ titanium tetrachloride. The container 196would remain in the position shown. By relocating the re~ractory tube in this manner, it would be very di~icult for magnesium to be forced out o~ the rsaction zone by a pressure surge.
; According to the invention herein, it i~ possible to retain all of the reactiv~ components o the proces~
within the closed system, with the only transfer of material being chlorine out o~ the cell or retort to and through the chlorinator and back to the retort. Thus chlorine i8 not consumed but merely serve~ as a carrier for titanium.
:lZEi~2~37 It should be understood that the single combined electrolytic/reaction cell concept of the invention provides substantial savings in energy as compared to the energy requirements of the various prior art reduction processes using magnesium metal. The magnesium, employed as the reducing agent in the process provided by the invention, is only melted once, that is, when it is formed by electrolysis. Likewise, the magnesium chloride is in the molten state due to the fact that the reduction reaction of titanium tetrachloride is exothermic. The magnesium chloride produced i8 obtained at temperature levels of about 1400F
and can be subjected to electrolysis in its molten state.
Conventionally, the electrolysis proceeds to production of magnesium metal, which is drawn off and cast as ingots. This requires placement of the magnesium ingot in a steel retort and melting since the reaction of titanium tetrachloride with magnesium requires the magnesium to be liquid.
Variations and modifications may be made to the structures which are illu~trated as preferred embodiments without departing from the spirit or scope of the invention as defined in the appended claims.
6~2~37 Winter, U.S. Patent No. 2,890,112 discloses another method for producing titanium metal by reduc~ion of the tetrachloride wherein both the magnesium and chlorine are recovered and recycled. winter suggests the use of sodium metal produced by electrolysis of a ternary salt along with a molten reaction calcium-magnesium alloy and chlorine gas. The chlorine gas is reacted with a tltanium ore/coke mixture. The reduction does not employ magnesium alone. A process involving molten sodium o~ten is dangerous and expensive.
Glasser et al, U.S~ Patent No. 2,618,549 provides a method ~or production of elemental titanium ~rom its ores by reductlon of a titanium halide such a8 titanium tetrachloride by means of an alkali metal amalgam such as is produced in mercury-amalgam chlorine cells used in the production of caustic ~oda. Chlorine produced in the electrolysis 18 employed to produce the titanium tetrachloride from the oxide ore.
The amalgam reactant is separated after lts productlon and added to a reaction vessel along with the titanium tetrachlorlde. The reduction reaction i~ carried out in the presence of an inert gas and with vigorous agitation of the reactants. When the reaction is completed, the product is transferred to a separating furnace without expo~ure to air using gravity or other feed means. The product is first distilled to drive of~ mercury and thereafter, the residual material is heated to above 1500F to separate sodium chloride. Subsequent purlflcation steps are suggested. Not only does the Glasser ~2~Z9~
process require the use of inherently dangerous mercury and sodium, it is expensive, requires much equipment and multiple steps as well as proximity and access to caustic soda processing plants.
Other processes are described in U.S. Patents to Maddex, 2,556,763; Blue, 2,567,838; Winter, Jr., 2,586,134; winter, Jr., 2,607,674S Winter, Jr., 2,621,121; Loonam, 2,694,653 and Dietz, 2,812,250.
Thus it is noted that the process of obtaining titanium metal from rutile ore by reduction thereof i8 well known. The conversion of the ore, which is in the form of an oxide, to the tetrachloride and reaction of the tetrachloride with magnesium metal to form magnesium chloride and titanium metal has been discussed. Titanium produced in this manner required considerable purification, both from impurities originating from the ore as well as removal of magnesium chloride trapped within the product and any remaining magnesium metal. Known processes often lncluded electrolytic processes where the production of magnesium metal was electrolytic. Magnesium was produced electrolytically isolated, removed from the cell and purified.
The purified magnesium metal then was remelted for the reduction reaction with the titanium tetrachloride. These processes were unduly expensive in terms of the energy requirements, the precautionary expedients required for safety (especially in view of the reactivity of magnesium and the need to separate and transfer 8ame), the number of steps and cost of purification, the waste of raw materials and loss in both transfer and purification.
~26~29'7 Of all the problems inherent in the conventional processes for reduction of titanium ore with magnesium metal, exposure of the magnesium metal to air was the most serious, particularly in terms of safety.
Conventionally, processes for producing titanium sponge include draining of the magnesium chloride from the reaction cell as the reduction reaction proceeds. The drained magnesium chloride is recycled by electrolysis producing magneslum metal, which is drawn from the cell and cast as ingots. These ingots then are placed in a steel retort and melted. The resulting molten magnesium is either transferred to another vessel for reaction with titanium tetrachloride or the molten magnesium charge reacted in the same vessel in which it was melted.
The reduction reaction of titanium tetrachloride with magnesium is exothermic, ~ith the by-product,magnesium chloride,heated to about 1400F. Thus the magnesium chloride i5 molten. Conventionally, the heat released in the exothermic reaction is lost, that is, not advantageously used.
Another problem encountered with conventional processes is the establishment of access both to the titanium metal produced, and to the magnesium chloride by-product. The reaction vessel conventionally has to be cooled. After cooling, operators using physical means such as jack-hammers or the like must literally break up the soldified material. The titanium metal resulting must be reined for obtaining the purity commercially desired. A
further danger encountered is the production of harmful amounts of phosgene gas resulting from the reaction of impurities in the ore with chlorine produced, or with the i26~297 magnesium chloride, under the elevated temperatures of the reactions.
The production of titanium metal i5 a very precise operation since the hot metal combine~ with oxygen, S n~trogen and moisture of the air. The metal also combine3 with carbon and most construction metals. ~efractory materials al~o are vulnerable to attack due to their oxygen content. Conkaminants produced render the resulting metal ~o hard and brittlo that it is useles~ for most application~. ~n~e 6uc~ co~taminant5 are picked up, there are no practical methods availa~le ~or removing such impuritie~. If one carries out the reaction under an atmosphere of an inert gas such as helium or argon at around 800C, the titanium alloys with the iron in the lS vessel to a minlmal extent. Neverthele~s, the metal layer in contact with the ve~sel wall aontain~ too much ixon to meet speci~iaation~ and must be disGarded.
In operation under conventional processe~, the magnesium ingots are picXled in dilute acid to remove surface oxidation ~ollowed by rinsing an~ drying steps.
~he dried magnesium charge i~ placed ln a cylindrical ~lat-bottomed steel pot. The oover i8 welded in place, the vessel te~ted for leaks and, if no lsaks are detected, all the air is removed from the ves~el by evacuation, followed by rele~se of the vacuum repeatedly with helium or a~on. The ve~el, ~ith the mAgnesium charge, is placed in 8 vertical aylindrical furnace ~nd heated either by ele¢tricity or Sy ~uol combustion. As soon a~
the magnesium ~egins to melt, purified titanium tetrachloride is ~ntroduced at a care~ully controlled rate.
J~
12~1~9'7 Inert g~s pressure within the vessel ~5 maintained to prevent lnward air leakage. The rate of lntroduction of the titanium tetrachlorlde i~ controlled such that excess heat generated in the vessel is dissipated through the veRsel walls, external heat being unnecessary to maintain the vessel temperature between 750 and 1000C.
Accordingly, improvements are sought in the recovery and in the purification of the recovered product with reduction in the danger, lowering of the costs, especially energy cost~, in¢rease in product purity and acce~ to the desired product.
The lesser handling the better and the lesser exposure o~ the reactants are important crlteria to be met.
126~Zg7 SUMMARY OF THE INVENTION
A system, including a single electrolytic/reaction cell,for obtaining titanium metal sponge from rutile ore ~y -c~nye~ting the rut~le,ore to titanium tetrac~loride in a separ-ate ves~el'and ~eeding the't~tanl`'um tetracfiloride to a combined electrolysis/reaction cell containing molten magnesium metal produced by electrolysis of magnesium chloride in that cell and reducing the titanium tetrachloride with the molten magnesium to produce titanium sponge and chlorine, diverting the produced chlorine to that vessel in which the titan$um tetrachloride is produced and the molten magnesium chloride produced by the reduction reaction is retained for subsequent electrolysis in the same cell.
Impurities in the ore are distilled from the reaction vessel in which the titanium tetrachloride is produced. Impurities in the titanium sponge are distilled therefrom.
~261;297 BRIEF DESCRIPTIO~ OF THE DRAWINGS:
FIGURE l is a diagramm~tic chart showing the chemical reactions involved with the system according to the invention and the relationship of the reactants and products thereof;
FIGURE 2 is a flow diagram illustrating the system of obtaining titanium metal sponge of high purity from rutile ore according to the invention;
FIGURES 3 A, B, C and D are graphic representationas illustrating the 8tages in the process accordin~ to the invention;
FIGURES 4 A, B and C are diagrammatic elèvational views in section illustratlng the combined electrolytic/reaction cell in the respective stages of the system a~ shown in FIGURES 3 A, B, C and D;
FIGURE 5 is a diagrammatic representation of one system according to the invention for obtaining titanium metal sponge;, FIGURE 6 i8 a diagrammatic representation similar to that of F~GURE 5 but illustrating a modified system;
FIGURE 7 is a diagrammatic elevational sectional representation of a chlorinator as employed in the systems of FIGURES 5 and 6;
~6~97 FIGURE 8 is a diagrammatic elevational sectional representation of a modified electrolytic/reaction cell according to the invention, and FIGURE 9 is a diagrammatic elevational representation in section of a further modified electrolytic/reaction cell according to the invention.
1~1297 DESCRIPTION OF PREFERRED EMBODIMENTS
.
As was noted hereinabove, the invention herein concerns a new and improved closed system for obtaining substantially pure titanium metal from its naturally abundant ores, such as Rutile ore. The system, and particularly the improved apparatus incorporated in said system, enables the production of titanium metal sponge of high purity with little loss of reactants empioyed and high efficiency of operation in its minimization of the use o energy, the invention being particularly characterized by the electrolyBi8 and t~ ~eductlon steps being performed in a single vessel.
The basis chemical reactions employed in the ~ystem according to the invention are as illustrated in FIGURE 1, the arrows therein illustrating the generation and recycling linkages.
Basically, magnesium chloride is electrolyzed to produce magnesium,which i8 employed as the reducing sgent reacted with a titanium halide and chlorine gas.
The chlorine gas iB employed as a reactant with titanium ore and coke to form titanium tetrachloride, the reactive halide to be reduced by the magnesium formed by electrolysis above mentioned. One typical composition of Rutile Ore that is representative is set out in the following ~able I.
TABLE I
RUTILE ORE
Australian TYPICAL CHEMICAL ANALYSIS
Tio 96.80% Guaranteed 2 95% Minimum Fe203 0.65 Zr2 0.96 SiO2 0.65 Cr203 0.18 V25 0.51 S 0.01 A123 0.22 CaO b.Ol MgO 0.06 PbO 0.06 Ignition Loss 0.15 T ~
Plus 52 Mesh 0.3 " 72 " 9.5 " 100 " 55,9 " 150 " 30.9 " 200 " 3.1 Pan Granular, 200 mesh, 325 mesh and 400 mesh available from Cincinnati in ~ags. Granular also available in bulk.
~.~61;~97 A mixture of coke (source of carbon) and said Rutile titanium ore is introduced into a vessel hereinafter referred to as a chlorinator, to which is added the chlorine gas produced during the electrolysis of magnesium chloride.
The magnesium produced in the electrolysis process is retained in the single electrolytic/reaction cell while the reaction between chlorine and the rutile ore/coke mixture takes place in the chlorinator. The product of chlorination, titanium tetrachloride, is returned to the electrolytic/reaction cell and reacted with the magnesium 80 a~ to produce titanium metal in sponge form and to replenish the supply of magnesium chloride in said electrolytic/reaction cell.
The temperature of the reaction is controlled to maintain a level sufficient to vaporize, for discharge, any impurities such as magne~ium metal, magnesiu~ oxide, trace elements, etc. which may have remained subsequent to the reduction reaction. Separate distillation may follow, The major purification of the Rutile Ore occurs during the chlorination process, where the trace elements, including iron, silicon zirconium, aluminum, vanadium and others, mostly as oxides, are converted to their respective chlorides and are discharged from the chlorinator along with titanium tetrachloride. The discharged titanium chloride is di~tilled for purification purposes prior to entry into the electrolytic/reaction cell for reaction with the magnesium, said magnesium ~eing retained within the electrolytic/reaction cell in which it i8 produced.
Referring to FIGURES 3 A, B, C and D as well as 4 A, B and C, there are illustrated electrolytic/reaction cells which characterize the invention herein as shown in the stages of ... . . . . . . ... . .. ... . .. .. . . . .. .........
æ~ 7 the process. The electrolytic/reaction cell generally is designated b~ reference character 10 and comprises a steel cylindrical vessel or retort having a removable upper section 12 and a lower section 14. A steel open-topped product container 16 i8 disposed within the lower section 14.
Container 16 i8 provided with a bottom or floor 18 and has plural drain openings 20 formed in the wall thereof closely adjacent to the floor 18.
Heating elements 22 are provided about the lower section 14. The upper section 12 of the cell 10 has a circum~erential flange 24 adapted to be seated sealably ~ecured to a like flange 26 on the lower section 14. The upper section 12 is fitted with a cover 28 sealably coupled thereto. Cover 28 has an axial passage 30 through which an elongate ceramic tube 32 is ~itted. The tube 32 is selected of a length whereby it extends into the open top of the Or~
container 16~hY~ht~ a sheath for the passage of the graphite rod 34 functioning as ~he anode.
The anode 34 extends upwa~dly through the cover 28 and out of cap 36 ~ealably secured o~to said cover 28 b~t insulated electrically therefrom by in~ulator 38. The cathode i~ container 16. The cap 36 has an outlet port 40 which is capable of ~eing coupled to conduits leading to the chlorinator ~to be described). Lifting rods 42 and 44 are passed through the cover 28 by way of seal me~bers 46. The li~ting rods 42 and 4-4 are coupled by weldiny or otherwise to the rim o~ container 16 for li~ting same into the section 12 when desired in the process, as shown in FIGURE 4C.
As shown in FIGURE 3A where the electrolytic/reaction cell 10 is in a condition shown in FIGURE 4A, a load of lZ~ 7 magnesium chloride is added to the lower section 14 of the cell 10. The section 14 is heated to about 1350F
to melt the magnesium chloride. The level of the liquid magnesium chloride is brought to a level L-l in the container 16. The upper section 12 with the associated anode 34 is seated onto the lower section 14 and bolted in place. A D.C. voltage at high amperage is supplied between the graphite anode 34 and the steel container 16 and the molten magnesium chloride is subjected to electrolysis to produce chlorine deposited at the anode 34 and magnesium metal. The chlorine gas is trapped within the tube 32 which surrounds said electrode 34 and is discharged by way of said port 40 to conduit means leading to the chlorinator.
The magnesium metal produced during the electroly~is proces~ deposits on the surface of the conta~ner 16 ~cathode)and rises upwaxd through the molten magnesium chloride toward the ~urface thereof. The tube 32 which vent~ the chlorine gas further serves as an electrical ln~ulator to prevent the magnesium metal, represented by reference character 48, which will float on the surface of the magnesium chloride, from short circuiting the electrolytic/reaction cell 10.
In the first cycle of operation, the electrolytic/
reaction cell 10 functions as an electrolytic cell for produc-tion of the magnesium metal which is used as the reducing agent, and the chlorine gas for delivery to the chlorinator. At a current efficiency of about 80~, approximately 8 kilowatt hours of power is required to produce one pound of magnesium.
The same amount of power,of course,produces three pounds of 12~12~'7 chlorine gas which leaves the cell 10.
FIGURES 3 (A, B, C and D) illustrate diagrammatically the stages of the process while the representations of FIGURES 4A, 4B and 4C illustrate the condition of the cell 10 at those stages respectively. FIGURES 3A and 4A
diagrammatically illustrate the cell 10 at the initial staye o~ the process just prior to the initiation of the electrolysls procedure. The first cycle consists of the electrolysis and the level L-l of the molten magnesium chloride i8 represented. At the end of the first cycle, the total liquid level L-2 iB lower than the level L-l at the start of the electrGlysis. This change in level results from the 1088 of three pounds of chlorine leaving the cell 10 for ~ach pound of magnesium produced. Particular attention thu~ is directed to FIGURE 3B illustrating the floating magnes~um metal 48 upon magnesium chloride remaining in the containex 16.
The second stage or cycle in the process is initiat-ed when there is sufficlent floating magnesium metal to reach the bottom of the refractory tube 32 illustrated in Figure 4A.
At this time, the anode 34 is withdrawn along with its surrounding refractory tube 32. If plural electroylsis/
reaction cells 10 are employed, the assembly o the anode 34 and its surrounding tube 32 is installed in a second 2S electrolysis/reaction cell and electrolysis initiated within that second cell 10. As illustrated in Figure 4B, a feed system 50 including valve 52 and piping 54 is coupled to the upper section 12 of cell 10 in substitution for the electrode assembly just removed. The feed system 50 links the supply of ,.. ,. ~,,. ~ ,"
titanium tetrachlorlde to said section 12 of cell 10.
The valve 52 i8 opened and titanium tetxachloride is introduced into the cell 10 to drop upon the open bed of floating magne~ium metal in the container 16. An inert gas, ~uch as argon from a source 56 thereof may be employed as a flushant during the feeding process by which titanium tetrachloride i8 introduced. Titanium metal i8 produced by reaction with the magnesium metal a8 shown in FIGURE 3C, the cell 10 ~eing illu3trated in thls reduction reaction stage in FIGURE 4B. Thu~, a~ter the reduction xeaction i8 completed, by which titanium metal and magnesium chloride i8 produced, the third stage or cycle is initiated, ~low o~ titanium tetrachloride being terminated. For each pound of magnesium metal in the cell 10 at the start of the sscond cycle, ~our pound~ of titanium tetrachloride i8 added to produce one pound of tltanium and ~our pounds o~ magnesium chLoride. The greater amount o~ the magnesium chloride remainlng at the end o~
the xeduction reaction ~loats upon the body of titanium metal ~pxoduced in ~ponge ~orm). Upon completion o~ said reduction reaction, the container 16 i8 raised within the lower section 14 to the upper ~ection 12 o~ cell 10 without exposing the a8ll interior to ~ir, to enable driinage of the magnesium chloride and cooling o~ the remaining body primarily of titanium metal sponge.
Once the titanium metal has cooled at least below 800F and pre~erAbly reached a temperature in the vicin~ty o~ 600F, tho cell 10 can be openod. ~he container 16 with its primarily titanium content can be removed. The titanium metal is not reactive at such temperature and hence the container 16 and the titanlum metal therein can be removed bodily and placed within a vacuum chamber (not ~hown) and heated to 1850F to boil off any entrapped magnesium chloride, as well a~ any remaining magnesium metal or magnesium oxide that may have ~een entrapped therewithin. Conventlonal cold traps ~not shown) may be provided for coupling to the vacuum chamber for receipt and condensation of the gaseous magnesium chloride, magnesium metal and magnesium oxide fraction~ for recovery and recycling back to the pxocess.
The chloxinator i~ illustrated in FIGURE 7 wherein the chlorine produced in the cell lO by electrolysis of chloride i~ recycled to prepare titanium tetra~hloride. The chlorinator, designated generally by r~ference 60, operates at about 1650~ and is raised to such temp~rature externally, S as by the furnace 62 surrounding same. Onae the react~on, ~i2 ~ 2 C ~ 2 C12 ~ iC14 ~ 2 CO ~ ~
i~ initiated, no further ~xternal heat i8 re~uired ~inca the said xeaction i8 exothermic. Either pressure transfer ~ystem 64 or a gravity transfer system 66 iB coupled to the chlorinator 60 to trans~er the titaniu~ tetrachloride produced therein to a speci~ic location ~or introduction to the cell 10.
rn Pre~g$ 5 the gra~i`ty trans~r ~yste~ 64 for the titanium tetrachloride i8 illustrated wn~le FIGURE 6 illustrates a pre~sure t~ansfer sys~em 66 ~ub~t$tuted in the system. The gravity trans~r ~y~tem 64 18 simpler th~n the pressure transfer ~ystem, containing many more valve~ and containers.
Howev~r, where the sites o~ in~tallation have relatively low roof8, there is a he~ght limitation maXing use of a pressure trans~er system imperatlve.
~L261297 Referring to FIGURE 5, a xepre8entation of an exemplary system i~ provided wherein the',re are a pair of cells lG and 10' used alternatively. Cell 10 ha~ just completed the electrolysis of magnesium chloride and contain~ two pounds of magnesium in it3 product container.
Cell 10' is at ready, with the magnesium chloride therein molten. At the moment electrolysis was completed in cell 10, power i8 switched from coll 10 to lO' to initiate electroly~is theroin.
~e~err~ng al~c to FIGU~ES 5, 6 and 7, $11ustrating more details o~ the ~ystcm, including chlorlnator~ 60 and 60', the titanlum cre i~ mixod with car~on ~n the ~orm o~ coke in mixer/~eed ~opper 74 and directed t~rough a feed sy~tem 76 including valves 78 and 80 to the inlet 81 at the top o~ the chlorinator 6~. L~ne~ 82 and 84~, carry the titanium tetrachloride proauce~ in the chlorinator 60 respectively to a receiving tan~ 86 via valve 88 and line 90 or to a purifie~ such as a distillation'still 68 via valve 92 and line 94. The line 94 snter8 the storage/feed tank 85 at inlet 98. The tank 86 is vented by way of line 100 via valves 102 to dry~r 104 which includes a bed of calcium chloride. Valve 106 controls passage through lines 108 and 110 to an exhaust 112 which may include a scrubber to prevent undesirable components ~rom esoaping to the atmosphere.
The purifier or still 68 is illustrated positioned intermediate the chlorinator 60 and the cell 10. Although a more pure titanium tetrachloride can be produced u~ing the ~till 68, th~ di~tillation step ~er~ormed thereby mav not be needed.
In the chlorinator 60, th~ ferric oxide is converted to ferric chloride, wh$ch is nonsolubl~ in titanium ; ,, ~26~2~7 tetrachloride and remains as a brown solid in the bottom of the titanium tetrachloride container. Zirconium oxide is converted to zirconium tetrachloride, same being a white solid which deposits on the condensor tubes of the still and/or on the wall 70 of the titanium tetrachloride storage container 86.
The zirconium tetrachloride does tend to clog the ~ystem and must be cleaned out periodically. Since zlrconium tetrachloride is soluble in water, periodic flushing with water will remove ~ame. The silicon ~ioxide in the ore is converted to silicon tetrachloride, which melt~ at -70C. and boils at 57C. Silicon tetrachloride and titanium tetrachloride are fully soluble in each other and hence the silicon in the ore will be carried over into the titanium metal produced, unless remedial action is taken.
Titanium tetrachloride boils at 136C while the boiling poi,nt of silicon tetrachloride is 57C. The container 8-6 for storing titanlum tetrachloride should be maintained above 57C, preferably at 70C. Under such temperature condition, the silicon tetrachloride produced in the chlorinator 60 will not condense in the titanium tetrachloride chamber container but will continue to and through the exhaust system. Vanadium oxide in the ore 25 i8 converted to vanadium tetrachloride (boiling at 152C) and is carried over into the ti~anium produced. Vanadium i~ not an ob~ectionable impurity and hence even if vanadium is carried over into the titanium product, it i~ not a serious problem.
1~612~
In FIGURE 6 the same basic system components as in FIGURE 5 are provided but the ~y~tem i~ pressurized and the feed from the chlorinator 60.to the titanium tetrachloride sterage tank 86'is a pressurized feed. The chlorinator 60~is supported on support structure 114 at ground level, with still 68' seated at ground level.
The titanium tetrachloride produced in the chlorinator 60' i~ pumped upwaxds to the storage tank 86' from the chlorinator 60~bY way of the still 68' and from there, to the ~to~age tank 86' located substantially above the electrolysi~/reaction ves~el or cell 10.
Looking at FIGURE 7, the chlorinator 60' comprise~ an inner core 116 formed o refractory tubing seated ln through pas~age 118 formed in surrounding electric furnace~ 62 and extending outward from the top 120 and floor 122 of said furnace 62 through a passage 124 formed in support 114. ~he opposite end~ of the core 116 are capped and ~ealed by upper cap 126 and lower cap 128.
Lower cap 128 includes the chlorine in~ection system 130, including an in~ector 132 having an outlet 134 and an inlet 136 extending outward of the cap 128. Inlet 136 i8 coupled into line 140 leading from the electrolysi~/reaction cell 10.
The upper cap 126 accommodates a pair of outlet ports 140 and piping 142, and a centrally locatod inlet port 144- Note that re~erence numeral 143 indicates the equivalent to lines 82 and 84 in FIGURE 5. One of the outlet pipo~ 142 1- ¢oupled through fail-safo pneum~tic ball valve 146 to line 94 loading to the ~till lnlet 150.
outlet line 152 extending ~rom t~e ~icin~ty of th.e floor of the ~till 68' is directed to ~he ~ece~vi~g tank 86 ~h~le :1261297 line 154 i~ directed to the scrubber/exhau~t 112'. The chlorinator 6o~8 illustrated as installQd in the pres~ure feed system of FIGURE 6. An intermediate ~econd still 15 can be interposed in ~he line 152 leading to the storage tanks 86 or 86' from which titanium tetrachloride i~ fed to the electrolysis/reaction cell 10.
The ore/coke feed system 76 preferably is a gravity/mechanically augmented system and comprises a cylindrical mixer/hopper 74 positioned with it~ outlet above inclined r~mp or belt arrangement 156 leaaing to the inlet 158 of chute 160, the outlet 162 of which is positioned to fQed tube inlet 164. Electrical vibrator~ 166 and 168 are arrange~ operatlve upon the belt arrangement 156 and upon the upper portion of ~eed tube 164 to assure continuity of lS feed of the orQ/coke mixture. The feed tube is formed of sections 170 and 172 coupled together and includes the pair of valves 78 and 80 whlch can be describe~ as ~ail-safe valves.
The ~ottom section 174 tQrminatQs at 81 interior of the upper end of the r~fractory (cer~mic) tube 116 o~ the chlorinator 60'.
Tho metho~ o~ feeding the Rutile ore/coke mixture to th~ chlorinator is simllar to the method of feeding the titanium tetrachloride to the Qlectrolysis/reaction vessel, although a very flowable sand-liXe mixture is treated.
The conventional ball valve used to control feeds cannot close well enough when ~ull of such sand-like mixture. Accordingly, vibrator 166 operates to ~ill a section 170 of the feed pipe above the ball vAlves. ~his section 170, a~ shown, cannot be over-filled. It has a volume which is less than the volume in the pipe sQction between the two valvQs, 78 and 80.
Once this upper section 170 of the feed pipe is filled, ~ . ~
~261297 material overflows to ramp 176 and activates an overflow detector 178 which stops the feeding mechanism. ~alve 78 then opens and drops the unit charge into the pipe , section 170 between valve~ 78 and 80. Valve 78 then closes and vaive 80 opens and drops the charge into the chlorinator 60' below ~y way of the remaining pipe 173. By allowing ~or the upper pipe section 170 to have a volume less than the volume between the two valves, a valve i8 never required to close when filled with the ore/coke mix. Of course, the feed rate is governed by the volumes of the pipe and the cy¢le rate. Over~lo,w collector 180 receive~ the ore/coke mixture overflow from ramp 176 and directs same back to hopper 74 via line 182.
Two modified embodiments of the invention are illustrated in FIGURES 8 and 9. ,These cell embodiments 10" and la'"1 differ from the earlier apparatus primarily in that the positions o~ the cathode and,anode have been rever~ed, the tubular anode now belng the outer tubular shell of the cell formea by a graphite crucible 184. This,electrode mu~t be fo~med by a machining proce~ from electrode grade graphite rather than a~ ordinary graphite crucibles (which are formed primarily of clay graphite).
One here exchanges the relativé positions o~ the anode and the cathode in the electrolysis/reaction cell 10 25 80 that completion of the electrolysis process i~ permitted with the reduction reaction producing titanium then'not only proceeding within the same ves~el but without changing top~ on the cell. With this arra,ngement, there is less opportunity ~or air to enter the system. Accordingly, the titanium thus produced will have lower oxygen content.
ix; ~: .
,................... ~
~26~
The bottom 186 of the graphite crucible 184 is covered with a disc 188 of refractory material simultaneously functioning as an electric insulator and to prevent the ~ormation of chlorine gas along the bottom 186. Chlorine is ~o~med along the sides of the graphite crucible 184 (the anode) and rises to the surface o~ the molten magnesium chloride, ex~ting through the top 190, as shown. Magne~ium is released at the cathode, floats as a li~uid body to the surface and i5 contained within the tube 214.
lQ Heaters 192 are provided for heating the outer surface of the crucible 184. Thermocouple 194 is provided for monitoring the temperature.
Magnesium chloride is heated by heaters 192 provided on the outer surface of the graphite crucible 184, with the addition o~ magnesium chloride continuing until the cell is ~illed to a level corresponding to ~-1 in FIGURE 3A.
For electrolysis a 7 ~olt D.C. voltage at 30Q~ Amps is directed from a source to the cell lQ to initiate the electrolysis. During the electrolysis process, chlorine gas is formed and deposited at the anode and leayes the cell, with the level within the cell being reduced to a level corresponding to L-2 in FIGURE 3B. At this point in the process, most o~ the liquid in the container196 is magnesium while all the liquid exterior of the product container i8 magne-sium chloride. Some liqu~d in container196 also will include some magnesium chloride since the container has openings in it which permit free passage of magnesium chloride through the container bottom. The li~uid magnesium floats on top of the magnesium chlor de. The electrolysis continues until a predetermined amount of the magnesium is produced. The level L-2 shown in FIGURE 3B represents containment of about ~6~2~7 two pounds of magnes~um metal. In order to produce four pounds of magnesium, one would start with a level L2 about twice as high as represented in level L-2 in FIGURE 3B.
Current requirements would ~e doubled, to 6000 Amps. The process ~ 24a -lX6~297 would take about one hour to produce about four pounds of the reducing agent, magnesiu~. The conta~iner 196 is equivalen~
to the container 16 of Figure 4 in function but inc~de~ a perforate bottom 198 to which a depending cylinder 200 is :
secured, as by welding. Cylinder 2Q0 is provided with drain passages 202. The ~e 214 is covered with disc 204 carrying elongate vertical tube 206, electrical connection being made thereto at 208.
The cell section 14' i8 Eormed by joining a pair of pipes 210,212 together defining a sheath for tube 214. ~ube 214 has a cap 216 through which tube 206 passes.
The feed system 76 is coupled to the upper end of tube 206. Tube 206 serves as the ca~hode an~ as a cohduit for feeding titanium tetrachloride to the magnesium once electrolysi~ is complete. The magnesium chloride formed during the reduction reaction i8 drained through perforate bot~om 198 and drain passages 202 remaining in ths crucible 184.
Tube 206 is weldably secured to perforate container cap 207.
The lower section 12' of cell 10" carries a cap 218 bolted to flange 220 by spring biased bolts 222.
The upper end o~ crucible 184 is secured in engagement with the cap 218 and electrical connection is made via the cap 218 by connector 224.
Once the reduction reaction is complete, the container 196 is raised within tube 214 for draining any magnesium chloride from the container 196.
In FIGURE 9 there i8 illustrated a ~urther modified embodiment of the invention generally designated by reference character 10"' and is similar to cell 10"
except that the anode comprises a graphite tube 226 positioned ;"
~126i297 to replace the graphite cruci~le 184 wh~ch functioned as tho anode in the embod~-ment illustrated ln FIGVRE 8.
The tube 226 i~ seated in a refractory bed 228.
The cathode is formed as a cylindrical rod 230 5 located secured to the floor 232 of the lower sect~on 14"
with an axial interior Calrod heating element 234. Electrical connection 236 i8 made to a heavy copper bu88 bar 238.
The ~owex input i8 coupled to one of the ~lange bolts 242 with the cover 244 being insulated electrically ~rom tho cell 10"'. A ~econd the~mocouple 246~may be introduce~ to the container 196'. ~ube 206 may be threadably connected to cap 207'. Otherwlse, the constructions of the eloct~oly~is/reactlon cells are similar.
In both FIGURES 5 and 6 the systems illustrated contain two reaction cells connocted to one chlorlnator 60 ox 60'. Throo r~action cells can bo grouped ~round one chls~nator at 120 spacing. ~wo of the cells could be cycled while tho th~r~ i8 down for maintonance, i.e., cleaning, ~tc.
By this mothod, a continuous process 18 obtalned, One ~ower ~upply ~8 noede~, and thls su~ply operates continuously, ~roduc~ng magnes~um and chlo~ine. ~he protuatlon o~ titanium in a cell would continuo until the product container i8 rea~onably full. Tho production rate of tho system iB govexned by the amount of power supplisd to it.
~he titanium sponge 18 purlfiod of any adhor~ng ~gC12 and magnesium metal by the conventional method o~ heat~ng to 1750-1800 in a vacuum. At this temperaturo ~n a vacuum, both MgC12 and m2gnesium boil o~f. They are rocovered and added back to the cells, as discussed earlier.
All valves employéd in the system o~ FIGURES 5 and 6 are of the pneumat~c, fail-safe des~gn. T~e valves open ~Trade Mark - 26 -with air pressure and are closed with a spring. Thus, if air pressure or electricity fail, the valves close. The valves are of all stainless steel parts with Teflon* seals. This type of valve has been found to be satisfactory to handle titanium tetrachloride (TiC14) as a liquid or a gas, and is also suitable for chlorine gas.
Looking back at FIGURES 5 and 6, the cell 10' is shown after completion of the electrolysis cycle and during a flush cycle prior to the introduction of TiC14. At the end of the flush cycle, valve 250 and valve 252 will close. All other valves will remain as described. To introduce the TiC14, first valve 250 is opened for a short period. This allows Ti-14 to ~ill the pipe section 254 between valve 250 and valve 252. Then valve 250 is closed. With valve 250 closed, valve 252 is opened. This allows the TiC14 between the two valves to drop into the cell below and thus onto the surface of the molten magnesium. The TiC14 reacts with the magnesium. Valve 252 then is closed. Valve 250 again is opened for a short period and then closed to allow the section of pipe between the two valves to fill with TiC14 again. Once valve 250 closes (a~ain), valve 252 may be opened to allow another charge of TiC14 to enter the cell below. Thus TiC14 may be added to the cell below at a controlled rate. The rate is determined by the volume of the pipe section between valves 250 and valve 252, and by the rate at which the valves are cycled. To determine a reasonable rate to feed the titanium tetrachloride (TiC14), thermocouple 246' is enclosed and monitored. The temperature within the lower section of the cell 10, 10', 10" and 10"' should be kept below 1500F.
~Trade Mark 126~2~
In the event of a malfunction in the cycling of valves 250 and 252, causing both'valves to be open at the same time, then the cell 10 below would explode. For this reason, the cell cover 244 is held on by spring biased S bolts 242. This method of securement serves two functions:
(1) A pressure buildup within the cell 10 will raise the' entire head to relieve such pressure. Thus the spring hold-down 242 acts as a safety valve; (2) the spring hold down 24Z also acts to assure good electrical contact between the cell top 244 and the graphite crucible 184 inside, Wlthout this spring pressure, the outer steel shell of the cell 10" and 10"' would expand in length dur~ng heatup. This increase in length would lead to poor contact between the cell top 244 and graphite crucible 184.
S$nce the system must carry 6000 amps, good contact must be maintained.
An expansion chamber 258 is provided with valve 260, Valve 260 remains open while titanium tetrachioride is belng added to the'cell 10" or 10"'. Its function is to e~ualize pressure between the area above the molten magne~ium within the container 16 and the area above the molten magnesium chloride ln the graphite crucible 184.
When a unit charge of titanium tetrachloride is dropped from valve 252 on the surface of the molten magnesium, there is a pressure ~urge. Of course, much happens in a very short time durlng this part of the cycle. First, the titanium tetrachloride changes state from li~uid to gas due to the high temperature, but at the same time, it i~
reacting (either as a liquid or a gas) to form solid ,. . . . . . .. .. . .... _,. __ 1~6~
titanium sponge, and li~uid magnesium chloride. One observes a sharp pressure surge rapidly decreasing to normal, a~d an increase in the bath temperature. The pressure surge could cau~e a problem within the cell. I~
S not compensated fox by connecting the innex and outer sect~ons of the cell with valve 260 the pres~ure surge could force the level of magnesium down in the container 16 Thls would force some of the magnesium out through the bottom of the container 16 ~nd into the outer cell chambe~. Magnesium thu~ ~orced out would be lost to the process. It would be recovered, however, when the cell i~ operated electroly~ically, since the chlorine produced would react with it to form magnesium chloride. ~hus the cell would "clean" ltself in the event this occurred.
The ~arge volum~ expansion chamber 258 helps dampen the pxe~sure surg~. One addit~onal feature has been incoxporated to help h~ndle n pxessure surge, if such a surge bacomes a problem. The refraatoxy tube ¢an be lowered from the po3ition shown in ~IGURES a ox g to the bottom o~ the cell. This can be done prior to the addition o~ titanium tetrachloride. The container 196would remain in the position shown. By relocating the re~ractory tube in this manner, it would be very di~icult for magnesium to be forced out o~ the rsaction zone by a pressure surge.
; According to the invention herein, it i~ possible to retain all of the reactiv~ components o the proces~
within the closed system, with the only transfer of material being chlorine out o~ the cell or retort to and through the chlorinator and back to the retort. Thus chlorine i8 not consumed but merely serve~ as a carrier for titanium.
:lZEi~2~37 It should be understood that the single combined electrolytic/reaction cell concept of the invention provides substantial savings in energy as compared to the energy requirements of the various prior art reduction processes using magnesium metal. The magnesium, employed as the reducing agent in the process provided by the invention, is only melted once, that is, when it is formed by electrolysis. Likewise, the magnesium chloride is in the molten state due to the fact that the reduction reaction of titanium tetrachloride is exothermic. The magnesium chloride produced i8 obtained at temperature levels of about 1400F
and can be subjected to electrolysis in its molten state.
Conventionally, the electrolysis proceeds to production of magnesium metal, which is drawn off and cast as ingots. This requires placement of the magnesium ingot in a steel retort and melting since the reaction of titanium tetrachloride with magnesium requires the magnesium to be liquid.
Variations and modifications may be made to the structures which are illu~trated as preferred embodiments without departing from the spirit or scope of the invention as defined in the appended claims.
Claims (38)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing titanium metal sponge in a stepwise operation within a closed cell system which includes an electrolytic anode and an electrolytic cathode comprising the steps of:
A. electrolytically decomposing molten magnesium chloride into magnesium metal and chlorine gas within the closed cell to form said magnesium metal as a molten layer upon said magnesium chloride;
B. terminating said electrolytic decomposition, and subsequently, C. directly contacting titanium tetrachloride with said layer of magnesium metal for effecting a reduction reaction therebetween within the same closed cell to form titanium metal sponge and magnesium chloride;
D. cooling the titanium metal sponge to a temperature whereat it is non-reactive with air; and.
E. removing said titanium metal sponge from said closed cell, excluding air from the closed cell during both the electrolytic decomposition and the reduction reaction until the temperature of the titanium metal sponge reaches said non-reactive level.
A. electrolytically decomposing molten magnesium chloride into magnesium metal and chlorine gas within the closed cell to form said magnesium metal as a molten layer upon said magnesium chloride;
B. terminating said electrolytic decomposition, and subsequently, C. directly contacting titanium tetrachloride with said layer of magnesium metal for effecting a reduction reaction therebetween within the same closed cell to form titanium metal sponge and magnesium chloride;
D. cooling the titanium metal sponge to a temperature whereat it is non-reactive with air; and.
E. removing said titanium metal sponge from said closed cell, excluding air from the closed cell during both the electrolytic decomposition and the reduction reaction until the temperature of the titanium metal sponge reaches said non-reactive level.
2. The process as defined in claim 1 comprising the step of directing the chlorine gas produced as a by-product of said electrolytic decomposition to react with a titanium ore/coke mixture under suitable conditions in a separate chlorinating apparatus to form the titanium tetrachloride employed to effect said reduction reaction and directing the thus produced titanium tetrachloride to said closed cell.
3. The process as defined in claim 1 or 2 further comprising the step of removing the electrolytic anode employed in said electrolytic decomposition from said closed cell without introducing air into said cell, said anode being removed subsequent to said termination of said electrolytic decomposition and prior to said contacting of titanium tetrachloride with said magnesium metal.
4. The process as defined in claim 1 or 2 further comprising the step of depositing said titanium metal sponge into a perforate container within said closed cell, raising said container within said closed cell in order to enable drainage of any magnesium chloride from said titanium metal sponge again without exposure of said closed cell interior to air, prior to said removal of titanium metal sponge from said closed cell.
5. The process as defined in claim 1 or 2 further comprising the step of depositing said titanium metal sponge into a perforate container within said same closed cell, raising said container within said closed cell in order to enable drainage of said magnesium chloride from said titanium metal sponge again without exposure of said closed cell interior to air and prior to said removal of titanium metal sponge from said closed cell, the step of cooling being performed while the titanium metal sponge is within said container.
6. The process as defined in claim 1 or 2 further comprising the step of gravitationally separating the titanium metal sponge from the magnesium chloride subsequent to completion of said reduction reaction.
7. A closed system producing titanium metal sponge in a stepwise operation comprising: a single vessel cell having an anode and a cathode and being operable electrolytically to produce magnesium metal and chlorine from magnesium chloride, first conduit and feed means to direct the electrolytically produced chlorine to the exterior of said single vessel cell, an electrical power source connected to said anode and cathode and means for terminating the electrolysis when a predetermined quantity of magnesium metal is formed as a floating liquid body on the magnesium chloride in the said single vessel cell, an exterior source of titanium tetrachloride, a second conduit and feed means for directing the titanium tetrachloride from said source to said single vessel cell only after the completion of said electrolysis for effecting a reduction reaction therein with the floating liquid body of magnesium metal to produce titanium metal sponge and magnesium chloride, means separating said latter reaction products within said single vessel cell, a cooling device for cooling said separated titanium metal sponge to the temperature at which it is non-reactive with air, and a device for withdrawing the cooled titanium metal sponge from said single vessel cell, the electrolysis and the reduction reactions taking place within said single vessel cell without exposure to air until the titanium metal sponge produced by the reduction process reaches a temperature at which it is non-reactive with air.
8. The system as defined in claim 7 and a chlorinator for reacting titanium ore with coke and chlorine to produce titanium tetrachloride, said first conduit and feed means directing the chlorine electrolysis product to said chlorinator, said second conduit and feed means directing the titanium tetrachloride product of said chlorinator to said single vessel cell.
9. The system as as deined in claim 7 and including a heating device exterior of said single vessel cell for heating the separated titanium metal sponge to a temperature required selectively to vaporize as distillates any residual magnesium, magnesium oxide and magnesium chloride therefrom and a distillate recovery device for recovering said distillates.
10. The system as defined in claim 7 wherein said cathode is a container movably located within said single vessel cell, said anode being disposed within the container to effect electrolysis while said container is located within a lower section of said single vessel cell, said container being adapted to be raised selectively from said lower section to an upper section of said single vessel cell and said container having a perforate bottom wall to facilitate gravitational separation of the titanium metal sponge reduction product from the resulting magnesium chloride reduction product when raised to said upper section while said single vessel cell remains sealed subsequent to completion of the reduction reaction.
11. The system as defined in claim 10 in which said anode is formed as a graphite rod, said graphite rod being introduced into said container when the latter is in the said lower section.
12. The system as defined in claim 7 wherein said single vessel cell has a container movably located therein, said container having an extension comprising said cathode, said anode comprising a graphite crucible defining the lower interior section of said single vessel cell and said container being disposed within said crucible to effect electrolysis while said container is located within a lower section of said single vessel cell, said container being adapted to be raised selectively from said lower section to an upper section of said single vessel cell and said container having a perforate bottom wall to facilitate gravitational separation of the titanium metal sponge reduction product from the resulting magnesium chloride reduction product when raised to said upper section while said single vessel cell remains sealed subsequent to completion of the reduction reaction.
13. The system as defined in claim 12 in which said extension comprises a generally solid electrically conductive rod electrically connected through the lower section of said single vessel cell at its lower end and to the bottom of the container.
14. The system as defined in claim 12 further comprising a heater surrounding the lower end of said anode.
15. The system as defined in claim 10 in which said anode comprises a graphite tube introduced into said container when said latter is in the lower section.
16. The system as defined in claim 7 in which the second conduit and feed means include a pair of fail-safe valves spaced apart along a conduit.
17. The system as defined in claim 8 in which there is a still along said second conduit and feed means between the chlorinator and said single vessel cell for purifying said titanium tetrachloride prior to feeding the latter to said single vessel cell.
18. The system as defined in claim 7 in which said upper section comprises an elongate cylindrical tube.
19. The system as defined in claim 8 in which the upper section is sealed and covered, said first conduit and feed means being coupled to said upper section through the cover, an expansion chamber arranged between said chlorinator and said upper section and a valve arrangement to prevent pressure surges in said first conduit and feed means.
20. The system as defined in claim 8 in which there is a feed means for introducing titanium ore/coke mixture to said chlorinator comprising upper and lower coupled coaxial superposed vertical conduits and a pair of spaced valves associated with said conduits, a hopper for supplying said mixture to said upper conduit and a vibrator for aiding flow of said ore/coke mixture through said conduits, said vibrator being disposed 80 as to operate upon one of said conduits.
21. The system as defined in claim 12 further comprising a power input electrically coupled between said power source and said lower section.
22. The system as defined in claim 20 in which the conduits are partially nested one within the other, the upper one of said valves is adapted to be opened to fill the lower one of said conduits, thereafter to be closed and the lower one of said valves is adapted to be opened to release the contents of said lower one of said conduits into said chlorinator.
23. The system as defined in claim 20 in which the conduits are partially nested one within the other, the upper one of said valves adapted to be opened to fill said lower one of said conduits, thereafter to be closed and the lower one of said valves adapted to be opened to release the contents of said lower conduit into said chlorinator, said upper conduit having greater volume than the lower conduit.
24. The system as defined in claim 7 in which said single vessel cell is isolated from exposure to air until the titanium metal sponge formed therein has cooled to a temperature below the reaction temperature of titanium with air, said single vessel cell having a container located therein for holding a molten charge of magnesium chloride, said container being the cathode and having a perforate floor, and said anode and cathode being arranged within said single vessel cell for effecting the electrolysis of said molten magnesium chloride, said anode being removable from said single vessel cell interior upon completion of said electrolysis without introducing air thereinto, the said single vessel cell formed of a pair of sealably coupled superposed coaxially arranged single vessel sections adapted to be separated for gaining access to the titanium metal sponge produced subsequent to cooling thereof and a lifting arrangement to raise the container from the lower section to at least the vicinity of said upper section when the reduction reaction is completed.
25. The system as defined in claim 24 in which said titanium tetrachloride feed means include a valve for introducing an inert gas as a flushant simultaneously with the introduction of said titanium tetrachloride.
26. The system as defined in claim 7 in which said single vessel cell is isolated from exposure to air until the titanium metal sponge formed therein has cooled to a temperature below the reaction temperature of titanium with air, said single vessel cell having a container located therein for holding a molten charge of magnesium chloride, said container having a perforate floor, said single vessel cell formed of a pair of sealably coupled superposed coaxially arranged vessel sections capable of being separated for gaining access to the titanium metal sponge produced subsequent to cooling thereof and a lifting arrangement to raise the container from the lower section to at least the vicinity of said upper section when the reduction reaction is completed, said feed means comprising a pressure feed arrangement.
27. The system as defined in claim 7 in which said single vessel cell is isolated from exposure to air until the titanium metal sponge formed therein is cooled to a temperature below the reaction temperature of titanium with air, said single vessel cell having a container located therein and holding a molten charge of magnesium chloride, the container having a perforate floor, said single vessel cell formed of a pair of sealably coupled superposed coaxially arranged vessel sections capable of being separated for gaining access to the titanium metal sponge produced subsequent to cooling thereof and a lifting arrangement to raise the container from the lower section to at least the vicinity of said upper section when the reduction reaction is completed, said feed means comprising a gravity feed arrangement.
28. The system as defined in claim 8 in which said single vessel cell is formed of a pair of superposed upper and lower communicating sections, an open-topped container is seated within sail vessel cell in the lower section thereof, a cap is seated atop said vessel cell and accommodates said anode therethrough to extend within said open-topped container, feed means for introducing a mixture of titanium ore ant coke to the chlorinator, the chlorinator capable of reacting chlorine with a mixture of titanium ore and coke to produce titanium tetrachloride, a conduit for directing the chlorine gas produced during electrolysis in said single vessel cell to said chlorinator for reaction with a mixture of titanium ore and coke, said first conduit and feed means directing titanium tetrachloride produced by said chlorinator to said container by way of said cap, a device operatively coupled to said container for raising and lowering said container between said sections of said single vessel cell, the sections of said single vessel cell being separable for removing the container upon completion of the reduction process and cooling of contents thereof, the container being disposed within the lower section during the electrolysis and reduction process and being disposed within the upper section subsequent of completion of reduction for drainage and cooling.
29. The system as defined in claim 28 in which said second conduit and feed means is capable of being selectively removed and replaced by said anode.
30. The system as defined in claim 28 in which said feed means for the titanium ore and coke mixture is operable to introduce said titanium ore and coke mixture into said chlorinator in controlled batches.
31, The system as defined in claim 28 in which there is provided a store for receiving and storing said titanium tetrachloride and feed means to direct the titanium tetrachloride to said store from the chlorinator.
32. The system as defined in claim 28 in which there is provided a store for receiving and storing said titanium tetrachloride and means to direct the titanium tetrachloride to said store from the chlorinator, said second conduit and feed means being pressure operated.
33. The system as defined in claim 28 in which there is provided a store for receiving and storing said titanium tetrachloride and means to direct the titanium tetrachloride to said store from the chlorinator, said second conduit and feed means being a gravity feed.
34. The system as defined in claim 28 in which said feed means for directing the titanium ore/coke mixture to said chlorinator comprises a hopper for holding said mixture, a hollow column including upper and lower column sections coaxially arranged superposed for receiving said mixture from said hopper, said upper and lower column sections being coupled one to the other, first and second valves operatively coupled to said columns for permitting filling of the column sections in serial stages with the upper column section filled first, then emptied to fill the lower column section and thereafter the contents of said lower column section being dispensed to the chlorinator and a ramp for catching any overflow of the mixture being transferred from the hopper of the column and a trough for receiving any of said mixture from said ramp.
35. The system as defined in claim 34, in which said upper column has a greater volume than the lower column.
36, The system as defined in claim 34 in which the titanium ore/coke mixture is introduced at the upper end of said chlorinator.
37. The system as defined in claim 31 in which the second conduit and feed means includes a distilling arrangement for separating fractions of the chlorinated product from the chlorinator which boil at temperatures lower than titanium tetrachloride prior to the delivery of the titanium chloride to said store.
38. The system as defined in claim 31 in which the second conduit and feed means include a distilling arrangement for separating fractions of the chlorinated product from the chlorinator which boil at temperatures lower than titanium tetrachloride prior to the delivery of the titanium tetrachloride to said store, the distilling arrangement including a pair of successively operated stills coupled serially in said last mentioned feed means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000453369A CA1261297A (en) | 1984-05-02 | 1984-05-02 | Electrolytic recovery process and system for obtaining titanium metal from its ore |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000453369A CA1261297A (en) | 1984-05-02 | 1984-05-02 | Electrolytic recovery process and system for obtaining titanium metal from its ore |
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| Publication Number | Publication Date |
|---|---|
| CA1261297A true CA1261297A (en) | 1989-09-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000453369A Expired CA1261297A (en) | 1984-05-02 | 1984-05-02 | Electrolytic recovery process and system for obtaining titanium metal from its ore |
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|---|---|
| CA (1) | CA1261297A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114317966A (en) * | 2022-01-14 | 2022-04-12 | 新疆湘晟新材料科技有限公司 | Arrangement method of reduction distillation device and magnesium electrolytic cell device for titanium sponge production |
-
1984
- 1984-05-02 CA CA000453369A patent/CA1261297A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114317966A (en) * | 2022-01-14 | 2022-04-12 | 新疆湘晟新材料科技有限公司 | Arrangement method of reduction distillation device and magnesium electrolytic cell device for titanium sponge production |
| CN114317966B (en) * | 2022-01-14 | 2023-08-18 | 新疆湘晟新材料科技有限公司 | Arrangement method of reduction distillation device and magnesium electrolytic tank device for producing titanium sponge |
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