EP0000498B1 - A flow process for chlorinating ferruginous titaniferous material - Google Patents

A flow process for chlorinating ferruginous titaniferous material Download PDF

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EP0000498B1
EP0000498B1 EP78100363A EP78100363A EP0000498B1 EP 0000498 B1 EP0000498 B1 EP 0000498B1 EP 78100363 A EP78100363 A EP 78100363A EP 78100363 A EP78100363 A EP 78100363A EP 0000498 B1 EP0000498 B1 EP 0000498B1
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iron
titanium
chlorides
reaction zone
process according
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German (de)
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French (fr)
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EP0000498A1 (en
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James Paul Bonsack
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S C M Corp
SCM Corp
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S C M Corp
SCM Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C22B34/1218—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by dry processes
    • C22B34/1222—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by dry processes using a halogen containing agent

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  • This invention relates to the recovery of the titanium values in titaniferous materials and more particularly to recovery of such values by chlorination techniques.
  • Such selective chlorination is accomplished with chlorinating agents of ferrous chloride, ferrous chloride and C1 2 , ferrous chloride and HCI, and HCI in combination with at least two of the following members of the group consisting of FeCl 2 , FeCl 3 , and C1 2 .
  • U.S. Patent No. US - A - 3,989,510 wherein the selective chlorination of the titanium constituent of the ore is accomplished by charging a hot chlorinator (1535-1950°C) with the ore, silica, alkali metal or alkaline earth metal chloride, and carbonaceous reductant. Products formed are vaporous TiCl 4 , molten metallic iron, and molten silicate flux containing various of the ore impurities.
  • a total chlorination process comprises chlorinating the iron-bearing titaniferous material at elevated temperature with chlorine gas in at least stoichiometric proportion for formation of titanium tetrachloride and iron chlorides.
  • the disadvantages of total chlorination techniques are obvious and include loss of chlorine in the form of iron chlorides, contamination of product titanium tetrachloride stream with iron chlorides, and a substantial waste disposal problem of such iron chlorides formed in the process.
  • the present invention is a flow process for chlorinating ferruginous oxidic titaniferous material having an iron to titanium molar ratio (Fe/Ti) of x:1, x being a positive number of at least 0.25 for producing titanium chlorides and by-product metallic iron.
  • Such flow process comprises passing through a reaction zone maintained at 1050°-1950°C.
  • a preferred embodiment of the present invention is a flow process for essentially completely chlorinating the titanium content of iron-bearing titaniferous solids whereby said iron is converted to metallic form.
  • Such flow process comprises passing said mixture in substantially laminar flow through the reaction zone maintained at about 1350 0- 1950 0 C, the atomic ratio of carbon in said mixture relative to the oxygen content in said mixture being greater than 1:1 for formation of CO, the ratio of the moles of chlorine in said chlorinating agent to said titanium in said titaniferous solids being not substantially above about 2 and the ratio of iron to titanium (Fe/Ti) in the titaniferous solids passed into said zone being not above 2.
  • the (Fe/Ti) ratio and the reaction zone temperature are those whereby the net chlorination of said titanium and reduction of said iron is in a steady state.
  • a product mixture containing titanium chlorides comprising titanium tetrachloride, metallic iron, carbon monoxide, and iron chlorides comprising ferrous chloride.
  • the iron chlorides are separated from said withdrawn product stream and are recycled to said reaction zone.
  • titanium trichlorides contained in the product stream are oxidized with make-up chlorinating agent to titanium tetrachloride and the iron chlorides are separated from said withdrawn product stream by quenching, such as with liquid titanium tetrachloride.
  • Advantages of this preferred embodiment of the present flow processes include that essentially pure product titanium chlorides are withdrawn from the process and the iron in the titaniferous feed is removed as elemental iron, i.e. essentially no iron chlorides are contained in the crude titanium chloride product stream withdrawn from the process. Iron chlorides formed in the reaction zone are withdrawn therefrom and are recycled to the reaction zone for efficiency and economy (i.e. no net loss of chlorine as iron chloride and prevention of iron chloride contamination in the crude titanium chloride product).
  • the present process involves no recycle of any components to the reaction zone, while the preferred embodiment of the invention includes a recycle of some unreacted iron chlorides exciting the reaction zone.
  • the basic thermodynamics and operating conditions for the process and for the preferred embodiment are distinct and such distinctions should be borne in mind throughout this applicatidn.
  • Figures 1 through 8 depict graphically the correlations of the three fundamental parameters for practice of the present process.
  • Figures 9 through 12 depict graphically the fundamental relationship between the Fe/Ti ratio in the feed and the reaction temperature for the preferred embodiment of the present process and provide further details for its operation.
  • Figures 13 and 14 are flow diagrams depicting two methods of practicing the preferred embodiment of the present process. Instrumentation, controls, feeders, fittings, pumps, and valves are not shown, but are to be provided where necessary or desirable in conventional fashion. Materials of construction for this process are 'conventional for this type of high temperature, corrosive operation.
  • the equipment can be composed of or lined with corrosion-resistant metals, alloy or refractory material (silica, fireclay, porcelain, etc.). Piping, duct work and the like will be of similar material and insulated where appropriate.
  • Various of the equipment and lines illustrated can be multiple, series, cascade, or parallel connected for additional treating time, capacity, or refinement of separation and/or purification. These drawings will be discussed later herein.
  • Figure 15 is a schematic drawing of the apparatus used in the Examples and will be described in connection therewith.
  • Ferruginous (iron-bearing) titaniferous material is the feedstock for the present process and, often, the term "ore" will be used for convenience as most titaniferous solids of interest will be an ore or derived from an ore source. Ilmenites are prime examples of such ores.
  • titaniferous ores relatively starved in titanium values and rich in iron values can be admixed with suitable titaniferous-rich slags or the like and such mixture provides a suitable source of feedstock for the present process.
  • chlorinating agent for the present invention most often will be chlorine gas and often the term "CI 2 " will be used herein for convenience and not by way of a limitation.
  • suitable chlorinating agents include organochlorides, and which can be fully chlorinated carbons (chlorocarbons) such as, for example, carbontetrachloride, or which can be partially chlorinated such as, for example, carbonylchloride (phosgene), hexachlorobenzene, and the like.
  • chlorinating agents include metallic chlorinating agents having less of an affinity for chlorine than has elemental iron, as shown by Othmer et al in "Metal Ordering by Chlorine Affinities for Oxides", Preprint of Paper Presented at the Metallurgical Society 102nd AIME Meeting, p. 13, (February 27, 1973).
  • a suitable chlorinating agent is hydrochloric acid (HCI), preferably in vapor form.
  • essentially complete conversion of the titanium to product titanium chlorides means conversions of at least about 75%, advantageously greater than about 85% and preferably greater than about 90%.
  • "essentially complete" conversion of titanium to titanium chlorides and of iron to metallic iron is achieved when at least about 75% of the titanium and iron are so converted and usually such conversions will be at least about 85% with conversions of greater than 90% quite practical in commercial scale operations.
  • titanium tetrachloride While the desired product of this process is titanium tetrachloride, it must be recognized that at the elevated temperatures of operation of the present process, significant amounts of titanium trichloride can be formed and most often a mixture of the tetrachloride and trichloride forms will be produced by the present flow process.
  • titanium chlorides For convenience the desired chlorinated titanium product will be referred to by titanium chlorides in this application.
  • the iron chlorides which also can form in the.present process most likely will be ferrous chloride at the elevated temperatures of operation for the present process, though it must be recognized that minor amounts of ferric chloride may also be found in the present process.
  • a key factor in the success of the present process is the recognition and correlation of several fundamental parameters which permit titanium chlorides to be produced without converting all of the iron in the feedstock to iron chlorides.
  • conversion of at least some of the iron in the feedstock to by-product metallic iron while production of some titanium chlorides is an improvement over and substantial step forward in the chlorination art, such as typified by total chlorination processes.
  • the stable species of iron and titanium can be produced by the reduction conditions existing in the chlorination zone. It is assumed that reduction precedes chlorination under the reduction-chlorination conditions provided in the present process.
  • the feedstock can be prereduced in conventional fashion.
  • FIGS 1 through 4 depict the mole percent of titanium in the feedstock converted to product titanium tetrachloride as a function of the molar ratio of chlorine in the chlorinating agent to titanium in the feedstock (CI Z /Ti) at various reaction temperatures for a feedstock having an Fe/Ti ratio of 1, 2, 5 and 20.
  • Feedstocks with Fe/Ti ratios of 5, and especially 20 are so rich in iron that they may be more properly classified as iron ores rather than titaniferous ores, though the present flow process can handle such ores for recovery of the titanium content therefrom.
  • Also shown on these drawings are the results for a state-of-the-art total chlorination process which is virtually independent of reaction temperatures above about 600°C. As shown in Fig.
  • Figures 5 through 7 depict graphically, at a given temperature for each of said drawings, the molar percent of iron in the feedstock which is converted to by-product metallic iron as a function of the feedstock composition, as given by the molar ratio of Fe/Ti, at various molar ratios of Clfii. From Figures 5 through 7, it is readily apparent that while conversion of 100% of the iron in the feedstock to by-product metallic iron is not feasible practically, the present process does permit significant conversion of the iron in the feedstock to by- product metallic iron while obtaining substantial conversion of titanium in the feedstock to product titanium chlorides (as shown on Figures 1 through 4).
  • the present process can, thus, be designed for commercial practice based upon economic and processing considerations because of the good flexibility which the process permits in predetermining the product composition of titanium chlorides and metallic iron at a multitude of values for the reaction temperature, the feedstock composition, and the proportion of chlorine consumed per mole of titanium in the feedstock.
  • reaction temperatures can range from about 1050° to 1950°C.
  • Advantageous reaction temperatures are from about 1250° to 1750°C and preferably about 1300° to 1600°C.
  • the feedstock composition Fe/Ti ratio can range broadly from about 0.25:1 to about 100:1, typically about 0.25:1 to 20:1, advantageously about 0.25:1 to 5:1, and preferably about 0.25:1 to 2:1 and more preferably between 0.25:1 and 1.65:1.
  • the molar ratio of chlorine to titanium (Clfii) will be greater than about 2:1 and preferably such ratio will be from about 2:1 to 3.5:1, and more preferably from 2.2 to 3.5:1 depending largely upon the feedstock Fe/Ti ratio.
  • Figure 8 depicts graphically the molar ratio of chlorine from the chlorinating agent to titanium in the feedstock (CI 2 /Ti) as a function of the Fe/Ti ratio in the feedstock at various temperatures which are required for conversion of all of the titanium in the feedstock to product titanium tetrachloride.
  • This drawing shows that the present process can be operated to convert virtually all of the titanium in the feedstock to product titanium chlorides over a wide range of feedstock compositions and over a wide range of reaction temperatures at a substantially constant ratio of CI 2 /Ti. It is interesting that the ratios of CI 2 /Ti are constant even at increasingly higher iron containing ores for converting virtually all of the titanium in the feedstock into titanium chlorides.
  • the overall or net reaction postulated for the preferred embodiment of the present process under steady-state conditions can be expressed conventionally as follows:
  • the foregoing reaction equation represents the overall or net reaction thought to be involved in the present process and is likely to be the result of several intermediate and/or competing reactions which can be theorized for the process.
  • Of prime importance to the present process is the recognition that the feedstock composition, as measured by the Fe/Ti molar ratio, substantially determines the outcome of the chlorination reaction when related to the reaction temperature.
  • reaction equation (I) the indicated molar ratio of chlorine to feed titanium in the feedstock is shown to be 2:1, but it is to be understood that with a minimum conversion of titanium in the feedstock to product titanium chlorides of about 75%, such ratio (CI 2/ fi) need only be 1.125:1 at very high temperatures assuming TiCI 3 as product and 1.5:1 at lower temperatures assuming TiCI 4 as product. Since a mixture of TiCl 4 /TiCl 3 likely is the product, the CI 2 /Ti ratio should be chosen according to the reaction conditions and feedstock actually used.
  • reaction equation (I) Three additional relevant reaction relationships can be developed from reaction equation (I) as follows: Note that all of the foregoing reaction relationships are based on the feed composition, Fe/Ti, which from reaction equation (I) has the value of x:1.
  • reaction ratio (la) can be related further to the reaction temperature and Fig. 9 depicts this relationship graphically as a plot of the molar ratio of iron in the feedstock to total iron (both recycle FeCI 2 and iron in the feedstock) entering the reaction zone as a function of the feed composition, as expressed by the ratio of Fe/Ti in such feed, at various temperatures of operation (isotherms) for the process.
  • This molar ratio (la) is a measure of the iron content in the recycle stream entering the reaction zone und steady-state operation of the process. Ideally,the value of this molar ratio is 1, i.e. no iron chlorides available for recycle; however, attainment of this is not practical and some iron chlorides will be recycled in the process.
  • steady-state conditions diagonal line, referred to above, defines a boundary of operation for the present process as measured by the Fe/Ti ratio of the feedstock and the reaction zone temperature and graphically is a portrayal of reaction ratio (la) at various reaction zone temperatures of the process.
  • steady-state conditions are attained when the overall reaction in the zone (i.e. net chlorination of the titanium and reduction of the iron) is in a steady-state (i.e. reaction is at equilibrium). This results in the proportion of iron chloride recycle being substantially constant.
  • Each point along the steady-state line corresponds to a minimum reaction temperature required to maintain steady-state operation of the process at a particular Fe/Ti ratio of the feedstock and with temperatures below which essentially complete conversion of all incoming Ti in the feed to product TiCI 4 and all incoming Fe in the feed to by-product Fe° will not be realized (i.e. a net increase of iron chlorides from the iron values of the feed admitted to the process).
  • the present process of course can be operated at a multitude of Fe/Ti values and reaction temperatures and the present process still retain the essential completeness of product TiCI 4 and by-product Fe° formation.
  • Temperatures of operation for this preferred embodiment should be at least about 1350°C in order to maintain a favorable equilibrium for formation of products and obtain reasonable rates of reaction.
  • At an upper temperature limit of about 1950°C essentially no iron chlorides are available for recycle, but attainment of this is probably not within present commercial operations, though thermodynamically it does appear theoretically possible.
  • Advantageous temperatures of operation for the present process range from about 1350° to 1650°C.
  • the feed composition is limited to Fe/Ti ratios of less than 2, and for practical commercial scale operations such ratios more often are from about 0.25 to about 1.65, and most often are about 0.5 to 1.5.
  • the values of the reaction ratios (Ib) and (Ic) are set. That is, the Fe/Ti ratio of the feedstock substantially deterines the amount of FeCI 2 recycle at a given reaction temperature.
  • Figure 11 depicts the reaction ratio (Ib) graphically as a function of reaction temperature at various values of the Fe/Ti ratio and
  • Figure 12 depicts reaction ratio (Ic) graphically as a function of reaction temperature at various values of the Fe/Ti ratio.
  • iron-bearing (or ferruginous) titaniferous solids are reacted with CI 2 in the presence of carbonaceous reductant for recovery of a stream of crude titanium chlorides and by-product elemental iron.
  • the first factor is that the amount of CI 2 provided from the chlorinating agent should be less than stoichiometric for conversion of all of the iron and all of the titanium in the feedstock into their respective chloride forms. In the preferred embodiment, however, it can be seen from reaction (I) that the amount of chlorine contained in the chlorinating agent should be approximately stoichiometric for formation of product TiCl 4 .
  • Chlorine gas chlorinating agent is preferable and suitably can be plant-grade chloride gas, such as normally found in titanium dioxide pigment plants which utilize chlorine gas for chlorination of titaniferous ores, so-called "chloride process". Other instances of readily available tonnage chlorine gas can be found in other commercial operations also.
  • chlorine gas need contain only about 60%-80% chlorine gas by volume with typical diluents such as nitrogen, oxygen, carbon monoxide and similar gases which are inert to the net chlorination reaction of the present process or are combustible for maintaining the reaction zone hot.
  • typical diluents such as nitrogen, oxygen, carbon monoxide and similar gases which are inert to the net chlorination reaction of the present process or are combustible for maintaining the reaction zone hot.
  • a second factor is that the amount of carbonaceous reductant should be at least stoichiometric for formation of. carbon monoxide with the oxygen content of all materials fed to the reaction zone in the reaction mixture (titaniferous feed, chlorinating agent and carbonaceous reductant).
  • titaniumiferous feedstock usually in oxide form.
  • the feedstock can be prereduced in conventional fashion prior to its passage into the reaction zone and the amount of carbonaceous reductant then would be based on the remaining oxygen (oxide) content in the prereduced feedstock fed to the zone (and other oxygen sources as mentioned above).
  • Conventional prereduction comprehends heating the feedstock under reducing conditions at a temperature of about 600° using hydrogen gas reductant to about 1200-1300 0 C. using a solid carbonaceous reductant for about 6 minutes on up to about 4-6 hours in order to reduce the oxidic titanium and oxidic iron in the feedstock.
  • the carbonaceous reductant is a finely-divided solid carbonaceous reductant such as, for example, coke, charcoal, carbon, coal, or the like.
  • the carbon content of some chlorocarbon chlorinating agents can provide the requisite carbonaceous reductant for the present process.
  • hydrocarbons such as, for example, benzene, acetylene, propane, and the like, can be successfully used as carbonaceous reductants for the present process.
  • Hydrocarbon reductants and the like can be used in the present process because of the discovery that the hydrogen content therein (and even in the combined water in the titaniferous feedstock) elutes from the zone predominantly as hydrogen gas and not as HCI even though free chlorine may be present in the mixture fed to the reaction zone.
  • the present process should be operated with a slight to moderate stoichiometric excess of titaniferous ore relative to the chlorine content in the chlorinating agent and of carbonaceous reductant relative to the oxygen content in the feed mixture.
  • pre-heating of the titaniferous feedstock can be quite beneficial to the process, especially when pre-reduction of the feedstock is practiced.
  • Such pre-heating can be a supplemental heat input to the reaction where the reaction zone also is heated, or the pre-heating step can be the total heat input to the reaction where no heating of the reaction zone is practiced.
  • This latter operational mode can be quite attractive to the overall process when combined with pre-reduction of the feedstock.
  • to such operation can be added a coking operation involving the conversion of coal (as the carbonaceous reductant) into coke.
  • the ore and carbonaceous reductant (when solid carbonaceous reductant is used) are fed to the process in finely-divided form.
  • Suitable such solids will be predominantly less than about 40 microns (weighted diameter average) and substantially all such solids should pass through a 325 mesh sieve (U.S. Standard Sieves Series).
  • High surface area of the ore and carbonaceous solids is believed to significantly influence completeness of the reaction, thus the finely-divided solids preference. Larger solids can be used, also, provided that they have a relatively high surface area, such as by being porous.
  • the ore and solid carbonaceous reductant can be admixed and fed to a conventional ball mill or similar attrition mill for reduction to the requisite size or can be subjected to fluid energy grinding tecnhiques. Screening or like conventional classification can aid in this step also. Size reduction of some types of ilmenite ores may be unnecessary as they naturally occur in finely-divided form, e.g. various beach sand ilmenites.
  • All flows and materials entering the reaction zone should be in admixture for prime operation of the process.
  • Such mixture can be obtained by suitable premixing of all feeds or by providing an initial premixing of all feeds or by providing an initial turbulent flow zone for proper mixing of the feeds.
  • the intimate mixture of feeds fresh ore, carbonaceous reductant, and chlorinating agent
  • Laminar flow is obtained conventionally when the Reynold's number (Re) for the fluid flow is less than about 2,000-3,000.
  • Re Reynold's number
  • dilute phase operation means that the weight concentration of solids entering the reaction zone (titaniferous feedstock and solid carbonaceous reductant, i.e. those solids not volatized in the zone) per unit volume of inlet gases in the mixture (i.e. vaporous chlorinating agents, vaporous reductants and diluent carrier gases, if any) will not substantially exceed about 20 kg/m 3 .
  • the initial solids loading will range from about 1.6 to 20 kg/c M 3 .
  • the entering gases are heated in the zone, they will substantially expand, thus lowering the solids concentration. Also, as more vaporous products are produced than enter the reaction zone, further dilution of the solids loading will occur. Thus, the initial solids loading is an upper limit for the process as the solids loading will continually decrease through the reaction zone from the feed inlet to the product outlet of the zone.
  • all solids in the zone are entrained in vapors or gases flowing through the reaction zone.
  • Such entraining gases and vapors typically include the inlet flow chlorinating agent and diluent carrier gases, if present, and product vapors formed from the reaction.
  • Elemental iron formed during the reaction in the reaction zone can be very sticky and can cause appreciable agglomeration of solids in the zone; thus conventional fluidized bed chlorination operations are to be avoided.
  • the present flow process minimizes (and substantially eliminates) occurrence of such agglomeration.
  • Back-mixing also prevalent in fluidized bed operations
  • Superficial vapor velocities in the neighbourhood of about 15 to 150 cm. per second generally are consistent with the requisite laminar flow (and dilute phase operation) for the present process.
  • the product stream withdrawn from the reaction zone contains titanium chloride vapors comprising titanium tetrachloride, carbon monoxide, elemental iron (if not already removed separately from the reaction zone), iron chlorides comprising ferrous chloride, and possibly unreacted carbonaceous reductant, and unreacted and partially reacted titaniferous solids (herein referred to as "processed titaniferous solids"). All chlorine from the chlorinating agent is reacted or consumed in the reaction zone. Most sources of iron-bearing titaniferous solids (notably, ores such as an ilmenite or the like) contain a variety of impurity metals (typically in minor amounts) which usually are chlorinated or reduced to elemental form in the reaction zone.
  • impurity metal chlorides or oxychlorides
  • Such impurity metals include, for example, niobium, vanadium (often recovered in oxychloride form), silicon, chromium, manganese, magnesium, tin, aluminum, and the like.
  • Such impurity metal chlorides or oxychlorides in the product stream are deemed to be part of the crude titanium chloride vapors withdrawn from the present process.
  • Elemental iron withdrawn from the chlorination zone can be separated from product titanium chlorides by magnetic separation, density separation, or the like.
  • titanium trichloride in the crude titanium chloride vapor stream advantageously is oxidized with make-up chlorine gas chlorinating agent to product titanium tetrachloride.
  • Vaporous iron chlorides, usually vaporous ferrous chlorides, withdrawn with the product titanium chlorides can be easily removed from the product stream by quenching the stream to a temperature of around 200°-600°C., for example, for conversion of the vaporous iron chlorides into solid state form.
  • the oxidized, purified titanium chloride stream then can be processed in conventional fashion, e.g. to produce Ti0 2 pigment.
  • reaction zone 12 fresh titaniferous solids and carbonaceous reductant solids 11, chlorinating agent 9, and iron chlorides recycle stream 24 are passed into reaction zone 12 which is maintained at about 1350° to 1950°C.
  • the titaniferous solids and carbonaceous reductant solids are in finely-divided form (i.e. less than 44 ⁇ m in size) prior to entering reaction zone 12.
  • Laminar flow is maintained through reaction zone 12, which suitably is a chlorinator, often with gradually increasing cross-sectional diameter for ensuring laminar flow therethrough.
  • the laminar flow in zone 12 is directed downwardly in a vertically arranged chlorinator so that gravity will work in the direction of flow.
  • atmosphere is maintained in reaction zone 12, though often a slight positive pressure is desirable to prevent air admission should equipment leaks develop.
  • an inert gas e.g. nitrogen
  • outlet 13 is provided to remove any solids which settle out or to remove molten elemental iron collected when the region near the product stream out is maintained above 1530°C, and this collection effort may be added with turbulent flow conditions thereat, if desired.
  • Product stream 14 (typically at about the reaction temperature) is withdrawn from reaction zone 12 and is passed into hot separation zone 16 which can be a cyclone or like separator. From hot separation zone 16 is withdrawn (a) overhead vapor stream 18 which contains crude TiCI 4 (including TiCl 3 ), carbon monoxide and vaporous iron chlorides (including FeCl 2 ) and (b) separated solids flow 17 which contains processed titaniferous solids (if any) and elemental iron (if not previously removed). Suitably, solids flow 17 is subjected to further separation (e.g., magnetic separation) for recovery of by- product elemental iron.
  • further separation e.g., magnetic separation
  • Any TiCI 3 in overhead vapor (product) stream 18 is oxidized with make-up chlorinating agent 19 to TiCl 4 .
  • Make-up chlorinating agent 19 generally is not much more in amount than is stoichiometrically required to oxidize the TiCI 3 in product stream 18 to TiCl 4 .
  • Product stream 18 then is quenched to a temperature of around 200°-600°C, with quenching stream 21 for conversion of the vaporous iron chlorides into solid state form and such quenched flow passed into cool separation zone 22.
  • quenching stream 21 is liquid TiCI 4 recycled from subsequent processing operations.
  • From cool separation zone 22 is withdrawn CO and crude TiCI 4 product stream 23, and iron chlorides solids 24.
  • Product stream 23 is sent to convention processing operations for subsequent conversion to Ti0 2 pigment or other desired titanium products.
  • Iron chlorides solids 24 can have additional chlorinating agent 26 added thereto for conversion of FeCI 2 solids into FeCI 3 in such stream as FeCI 3 can be transported as a vapor (b.p. 320°C).
  • additional chlorinating agent 26 will have to be taken into account and appropriate adjustment of chlorinating agent 9 made, if necessary.
  • the titaniferous solids can be pre-reduced and/or pre-heated before entering reaction zone 12.
  • Hot separation zone 16 and cool separation zone 22 can comprise three distinct zones.
  • the first zone can remove solid Fe°, and ore and coke fines.
  • the second zone can separate out impurity metal chlorides (e.g. MnCl 2 , CaCl 2 , MgCl 2 etc.) after its feed stream is cooled to about 310°C with liquid TiCl 4 .
  • the stream entering this second zone also may have CI 2 added for oxidizing TiCI 3 to TiCl 4 and FeCl 2 to FeCl 3 .
  • the third zone then can separate the FeCl 3 (s) after its feed stream is cooled with liquid TiCI 4 to about 200°C.
  • Various alternatives are possible, of course, such as is described for Figure 14 below.
  • salient features of this embodiment differing from the embodiment described in Figure 13 include use of coal as the carbonaceous reductant and provisions for converting the coal into coke. Also, the titaniferous feedstock and coke are pre-heated to such a temperature that no heating of the reaction zone is required. Further, feedstock and coke solids entering the process are larger in size (e.g. 50 ⁇ 100 + ⁇ m) so that the incompleteness of reaction is expected. Recycle of unreacted feedstock in reduced form is provided to prevent loss of titanium from the process.
  • titaniferous feedstock, coal, carbon monoxide, and air are fed through line 51 into reducing and coking zone 52 wherein the coal is coked and the titaniferous feedstock is conventionally reduced.
  • Exhausted from zone 52 through line 53 are carbon dioxide and nitrogen.
  • the reduced feedstock and coke are withdrawn from zone 52 through line 54 and passed into preheating zone 56.
  • the temperature in preheating zone 56 is maintained by passing molecular oxygen via line 57 into such zone in order to be combusted with carbon therein with carbon monoxide being vented from such zone through line 58.
  • the titaniferous feedstock and coke are preheated to such a temperature that when passed into reaction zone 61 subsequently, the desired reaction temperature will be maintained in reaction zone 61 without requiring heating of such reaction zone. It is possible, of course, to employ a single zone to simultaneously coke, reduce and preheat as explained above.
  • the titaniferous feedstock and coke are withdrawn from preheating zone 56 through line 59 and then passed into reaction zone 61, which suitably is a chlorinator. Within reaction zone 61 is maintained the requisite laminar flow as required in the process.
  • the chlorinating agent is ferric chloride/chlorine vapor recycle stream 92 which is passed into reaction zone 61 and this recycle stream will be explained later herein.
  • reaction zone 61 From reaction zone 61 all products are withdrawn through line 62 and passed into unreacted feedstock/coke separation zone 63.
  • This serparation zone separates the unreacted titaniferous feedstock and coke from remaining impure vapors (containing entrained fine solids such as Fe°) produced in the reaction zone and such solids are withdrawn from separation zone 63 through line 64 and passed into preheating zone 56.
  • the impure vaporous stream separated in separation zone 63 is withdrawn therefrom through line 66 and such stream contains mainly HCI, N 2 , TiCI 4 /TiCl 3 , FeCl 2 , solid Fe°, CO, and a variety of impurities (vaporous and/or solid) typical of conventional chlorination processes.
  • Such stream is passed into iron separation zone 67 wherefrom the solid metallic iron is separated and withdrawn through line 68.
  • the remaining vapors are vented from iron separation zone 67 through line 69 which then is combined with liquid TiCI 4 stream 71 a in order to cool the stream sufficiently to convert the vaporous ferrous chloride therein into solid state ferrous chloride and with CI 2 stream 70 in order to oxidize any TiCI 3 in the product stream into TiCl 4 .
  • This cooled stream then is passed into ferrous chloride separation zone 72. From ferrous chloride separation zone 72 is withdrawn overhead vapor stream 73 which is additionally cooled by liquid TiCI 4 stream 71 b to further cool the stream to assist in separation of impurities contained therein.
  • Such cooled stream is passed into primary impurity solid separation zone 76 wherefrom impurity solids are withdrawn through line 77 and product TiCl 4/ carbon monoxide are vented through line 78.
  • a typical analysis of the impurity solids withdrawn from line 77 would show such stream to contain impurities including aluminum oxychloride, zirconium chloride, and niobium oxychloride.
  • Ferrous chloride solids are withdrawn from ferrous chloride separation zone 72 through line 74 and passed into ferrous chloride conversion zone 79.
  • Ferrous chloride conversion zone 79 is maintained at a sufficient temperature in order to revolatilize the ferrous chloride solids passed therein and additionally the ferrous chloride is oxidized to ferric chloride by means of chlorine gas passed into such conversion zone through line 87.
  • the amount of chlorine gas used is sufficient to oxidize the ferrous chloride into ferric chloride (it is easier to transport vaporous ferric chloride by performing this operation) and additionally sufficient chlorine is fed in order that the amount of chlorine in molecular form and that half mole coming from the ferric chloride is sufficient to conduct the reaction in reaction zone 61.
  • the temperature of the ferrous chloride conversion zone 79 is maintained by use of sand conversion heating zone 81 which is fed with carbon monoxide and air through line 82 for combustion. Exhaust gases of carbon dioxide and nitrogen are vented from zone 81 through line 83. Conventional silica sand is quite useful in this sand conversion and heating zone 81.
  • the hot sand is passed through line 84 into ferrous chloride conversion zone 79 and the cooled sand is recycled to heating zone 81 through line 86 to complete the cycle.
  • the ferric chloride/CI 2 vapor stream is vented from ferrous chloride conversion zone 79 through line 88 and passed into secondary impurities solids separation zone 89 wherefrom remaining impurity solids are withdrawn through line 91.
  • impurity solids typically include magnesium chloride, calcium chloride, and manganese chloride.
  • From this secondary separation zone 89 is withdrawn the FeCl 3 /CI 2 vapor recycle stream 92 which serves as the chlorinating agent which is passed into reaction zone 61 in order to complete the process.
  • Hopper 111 contains the titaniferous ore/carbon mixture and is fed into line 115 by a screw feeder (not shown).
  • Nitrogen carrier gas 113 is used in order to ensure that no chlorine gas backs up in line 115 and to equalize the pressure in hopper 111 through pressure-equalizing line 114.
  • Chlorine gas chlorinating agent 116 enters line 115 and is combined with the ore/carbon mixture and nitrogen carrier gas flow.
  • the feed mixture (ore, carbon and C1 2 ) enters reactor 117 through inlet 109, which is insulated with insulation 108 which heat-seals reactor 117 and prevents premature heating of the reaction mixture.
  • Reactor 117 is a tubular furnace defining reaction zone 118.
  • Reaction zone 118 is tubular in shape with an ID of 5.2 cm. and effective length of about 30 cm (about half the total length of reactor 117). Since the outlet end of reactor 117 is not insulated, after about 30 cm in reaction zone 118, the temperature drops off sharply.
  • Several thermocouples also are disposed in reactor 117 in order to monitor the temperature of reaction zone 118.
  • samples of the product vapors were analyzed periodically by an in-line gas chromatograph (not shown).
  • the main flow of product vapors were directed into a tank of 10% sulfuric acid which also contained a small amount of a peroxide.
  • Product titanium chlorides are scrubbed from the product vapors and dissolve in the sulfuric acid tank (TiCl 4 complexes with the peroxide to give a visual confirmation of its presence).
  • Carbon monoxide and nitrogen flow through the acid tank and such flow is also periodically analyzed by another in-line gas chromatograph.
  • Reaction zone 118 is preheated with a flow of N 2 to about 1350-1400°C, after which the system is purged with argon. The argon is shut off and the feed solids and CI 2 flows are simultaneously commenced. The chlorination run is continued until steady-state is reached (constant gas compositions as measured by the in-line gas chromatographs), after which the run is discontinued and the products analyzed.
  • powdered iron was included in the feed in order to ensure that the possibility of a total chlorination reaction was not possible, i.e. all prior art is consistent in predicting that the foregoing reactants would not form any titanium chlorides.
  • Reduced ilmenite was made by heating a mixture of 70% by weight ilmenite and 30% by weight coke at a temperature of about 1200°C for three hours in a static bed with a slow purge of nitrogen.
  • the ilmenite/coke mixture had been ball-milled to the above-indicated size prior to the reduction operation.

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EP78100363A 1977-07-21 1978-07-11 A flow process for chlorinating ferruginous titaniferous material Expired EP0000498B1 (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US81758777A 1977-07-21 1977-07-21
US81771977A 1977-07-21 1977-07-21
US817587 1977-07-21
US05/885,442 US4183899A (en) 1977-07-21 1978-03-10 Chlorination of ilmenite and the like
US817719 1986-01-10
US885442 1997-06-30

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EP0000498A1 EP0000498A1 (en) 1979-02-07
EP0000498B1 true EP0000498B1 (en) 1981-10-21

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DE2960766D1 (en) * 1978-04-21 1981-11-26 Laporte Industries Ltd Production of titanium chlorides
JPS56501522A (it) * 1979-11-19 1981-10-22
ZA81604B (en) * 1980-02-19 1982-02-24 Laporte Industries Ltd Process for beneficiating oxidic ores
DE3007742A1 (de) * 1980-02-29 1981-09-10 Dornier System Gmbh, 7990 Friedrichshafen Verfahren zur herstellung von titantetrachlorid
IT1156318B (it) * 1982-09-08 1987-02-04 Samim Soc Azionaria Minero Met Procedimento per la produzione di cloruri metallici
US4442076A (en) * 1982-11-17 1984-04-10 Scm Corporation Entrained downflow chlorination of fine titaniferous material
US5660805A (en) * 1989-10-31 1997-08-26 E. I. Du Pont De Nemours And Company Method for beneficiating titanium-bearing material containing iron
JP6326405B2 (ja) * 2013-03-06 2018-05-16 東邦チタニウム株式会社 四塩化チタンの製造方法
EP4086228A1 (en) * 2021-05-06 2022-11-09 Kronos International, Inc. Chlorine recycle process for titanium-bearing feedstocks with high iron contents for the production of titanium tetrachloride based on the conversion of anhydrous ferrous chloride to ferrous sulfate with concentrated sulfuric acid

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US4017304A (en) * 1972-10-20 1977-04-12 E. I. Du Pont De Nemours And Company Process for selectively chlorinating the titanium content of titaniferous materials
FR2286881A1 (fr) * 1974-10-02 1976-04-30 Othmer Donald Fabrication de chlorure de titane, de rutile synthetique et de fer metal a partir de materiaux titaniferes contenant du fer

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EP0000498A1 (en) 1979-02-07
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IT7850432A0 (it) 1978-07-21
IT1105937B (it) 1985-11-11

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