Classifications

• • 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
  • C22B34/1263—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 metallic titanium from titanium compounds, e.g. by reduction
  • C22B34/1268—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 metallic titanium from titanium compounds, e.g. by reduction using alkali or alkaline-earth metals or amalgams
  • C22B34/1272—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 metallic titanium from titanium compounds, e.g. by reduction using alkali or alkaline-earth metals or amalgams reduction of titanium halides, e.g. Kroll process

Definitions

• the present invention relates to a process for the preparation of metallic titanium which comprises reducing tituanium tetrachloride with an alkali metal so as to provide metallic titanium which has a very minor hydrogen gas content and a low Brinell hardness.
• a process by one reaction step which comprises causing titanium tetrachloride to react with an approximately stoichiometrical amount of an alkali metal and thereby reducing it to titanium metal by a one stage method
• another process by two reaction steps which comprises causing titanium tetrachloride to react with a stoichiometrically insuificient amount of an alkali metal and producing a lower valency titanium chloride as the first step and further, adding a deficient amount of alkali metal to the said chloride for reducing it.
• a leach treatment is usually carried out in such a manner that the said reaction mixture is rinsed with a DETAILED large amount of water and alkali chloride in the said reaction mixture is made to eluviate and removed therefrom.
• metallic titanium sponge obtained by the said leach treatment contains a substantial amount of hydrogen and in the case of using the sponge for arc-melting hydrogen is separated and the thereby, the arc can not be stabilized. Further, there is a danger of explosion and safety of the melting operation is impaired and furthermore, the finished product has drawbacks, e.g. undesirably high Brinell hardness.
• Japanese patent publication No. 4304/1958 discloses using stoichiometrically, slightly insufiicient amounts of the alkali metal, to produce a metallic titanium sponge including a small quantity of low valency titanium chloride in the reaction compound and then, leaching the compound with an aqueous solution of mineral acid containing soluble phosphite.
• phosphorous acid is employed as the auxiliary raw material, so that the cost becomes expensive, and additionally, phosphorous acid is present in the waste solution produced in the leaching process and contains a large amount of alkali chloride, so that it is very diflicult to recover the alkali chloride from it.
• the temperature should be particularly selected in the range of from 600 to 800 C. in a first reaction stage which comprises making an alkali metal react with titanium tetrachloride and said temperature so as to reduce major portions of titanium tetrachloride to metallic titanium. Then, the reaction compound is heated at a temperature of from 900 to 950 C., as the second reaction stage, for a period of from 1 to 10 hours during which the first stage reaction compound is digested and the reaction is completed.
• the metallic titanium sponge so obtained can be very easily freed from alkali chloride and other impurities in a leaching process.
• the present invention has the advantage of curtailment of operting time, and savings of chemicals and industrial water. Also, a high purity titanium metal which has a low value of Brinell hardness is obtained.
• the amount of titanium tetrachloride used is selected to be 0.5 percent or more of the stoichiometric amount, preferably, from 1.0 percent to 2.0 percent excess stoichiometric amount in proportion to the quality of alkali metal used.
• a metal sponge of titanium, so obtained shows a beautiful metallic lustre and a lower Brinell hardness.
• the reason for the metallurgical reaction herein described is not entirely clear, but it is believed that when the main reducing reaction (the first reaction step) is carried out at the defined temperature range of 600 to 800 C. crystalline growth of metallic titanium favorably takes place and large size crystals are produced, so that the rinse in a leaching process is easily performed and further, as those crystals have inactive surfaces, the surfaces do not adsorb impurities, hydrogen gas.
• Formation of large size crystalline metallic titanium in accordance with the present invention is achieved only by performing the first reaction step i.e., reduction at a temperature of '600 to 800 C. If a temperature of below 600 C. is used, blackish titanium metal powder is produced and it requires a long time leaching process, and also, it has an active surface, so that it is apt to adsorb impurities or gas. On the other hand, if a temperature of over 800 C. is used, part of the high temperature treatment causes a local reaction, and some alkali chloride penetrates into the inner part of the titanium metal and it becomes hard to remove. In both cases, high purity of titanium metal can not be obtained.
• the first reaction step i.e., reduction at a temperature of '600 to 800 C. If a temperature of below 600 C. is used, blackish titanium metal powder is produced and it requires a long time leaching process, and also, it has an active surface, so that it is apt to adsorb impurities or gas.
• the reaction temperature in the present invention is measured at a midpoint between central part of the reactor and its peripheral part and a protective tube which is provided with thermocouple thermometer is located at a symmetrical position in contrast with the inlet for the raw material and cm. upward from the surface of a reaction mixture. If the protective tube of the thermocouple is directly immersed in the reaction mixture, metallic titanium and alkali chloride are deposited and solidify on an external wall of the protective tube and a thick layer which tends to impair the thermal conductively is formed thereon, so that, it is difficult to accurately measure the temperature of the reaction system. Additionally the position of the thermocouple must be kept at all times at 10 cm. or higher from the surface of the reaction mixture. Therefore, as the surface is raised by introducing raw material into the reactor, the position of the thermocouple must be drawn up gradually.
• the excess is selected from 0.5 percent or more of the stoichiometric amount.
• the selected amount is one percent or more of the stoichiometric amount, or two percent or less of said amount. If an excessive amount of titanium tetrachloride is employed, the excess titanium tetrachloride is not only consumed in vain but the reaction compound must also be treated with a high concentration of rnineralacid in order to inhibit the formation of titanium chloride hydroxide in the leach step.
• the alkali metal in accordance with the present invention is selected from sodium metal or potassium metal, but sodium metal is most desirable from an industrial viewpoint.
• conduits for inert gas are provided in a reactor for the alkali metal and titanium tetrachloride and a thermocouple thermometer is provided.
• the air in the reactor is substantially replaced with argon gas.
• the alkali metal is introduced in the reactor and reactor is heated at a temperature of 600 to 800 0., preferably at a temperature of 600 to 700 C. and then, titanium tetrachloride is gradually introduced by regulating the flow rate, so that a reaction temperature may be maintained in the range of 600 to 800 C.
• the total amount of alkali metal may be previously introduced into the reactor or a portion of the total alkali metal may be introduced simultaneously or alternately in the course of introducing titanium tetrachloride. Otherwise, a certain amount of reaction compound is previously placed in the reactor and then, alkali metal and titanium tetrachloride may be continuously introduced from one side and the reaction compound may be continuously taken out from the other side.
• the reactor When the reaction temperature exceeds the defined range, the reactor is cooled by blowing cool air on the external wall of the reactor, and when the temperature goes below the specified range, the reactor is heated in order to keep the temperature at the range of 600 to 800 C. until the raw material is completely introduced into the reactor.
• reaction compound After the introduction of the titanium chloride has finished, a reaction compound is obtained and this reaction compound is heated at a temperature of 900 to 950 C. for a period of at least one half hour, preferably between 1 to 10 hours. Thus, the reaction is completed, and the alkali chloride and metallic titanium are allowed to separate. Then, the product is cooled and rinsed with a large amount of water or aqueous solution of dilute mineral acid, particularly an aqueous solution of hydrochloric acid and metallic titanium sponge having a metallic lustre and of high purity is thereby obtained.
• EXAMPLE I 100 kg. of filtered, purified metallic sodium was charged into an iron reduction vessel under an argon gas atmosphere and the vessel was heated at 600 C. by means of an electric furnace. Then, 206 kg. of purified titanium tetrachloride was fed into the vessel by regulating the flow rate so the reaction temperature was kept in the range of 620 to 690 C.
• the amount of titanium tetrachloride employed is the stoichiometric quantity in which all titanium chloride is reduced to metallic titanium by the alkali metal fed into the vessel.
• a reaction compound in the said reduction vessel was crushed to a moderate particle size of about 2 mesh by means of a jaw crusher. Then the pulverized compound was leached with an aqueous solution of one percent hydrochloric acid for 2 hours after which it was rinsed with water for 2 hours. Then, the pulversized compound was dried at 60 C. under vacuum condition and thereby, metallic titanium sponge was obtained.
• EXAMPLE II The same reduction vessel in Example I was employed and 100 kg. of purified sodium metal was charged into the vessel under an argon gas atmosphere. The vessel was heated at 600 C. by means of an electric furnace and then, 209 kg. of titanium tetrachloride was fed into the reduction vessel by regulating the flow rate so that the reaction temperature was kept in the range of 650 to 730 C. In the course of about 5.5 hours, the feed operation was finished and then, the vessel was heated so that the temperature inside was kept at 950 C. The temperature was maintained for about 5 hours and the vessel was cooled. The amount of titanium tetrachloride employed as against the sodium metal was 1.5 percent in excess of a stoichiometrical amount.
• EXAMPLE III The atmosphere inside the reduction vessel in Example I was satisfactorily replaced by argon gas and 30 kg. of purified sodium metal was charged into the vessel. The vessel was heated at 600 C. and then, 61 kg. of purified titanium tetrachloride was dropped into the vessel while keeping the reaction temperature in the range of 600 to 720 C. Then, 65 kg. of sodium metal and 138 kg. of titanium tetrachloride were further dropped into the vessel while keeping the reaction temperature in the range of 600 to 720 C. The amount of titanium tetrachloride employed as against sodium metal exceeded 2 percent over a stoichiometrical amount. When the feeding of the reagent was completed, the reduction vessel was heated, that the temperature inside the vessel was raised to 930 C.
• Example II The reaction compound was crushed and then, it was similarly treated by the same process as described in Example I and metallic titanium sponge was thereby obtained.
• the metallic titanium indicated a Brinell hardness of 83 and 0.0022 percent of hydrogen content.
• EXAMPLE IV For the purpose of comparison, the reaction was carried out by the same procedure as described in Example II with with the only exception that the reaction temperature was maintained in the range of 400 to 500 C. Otherwise, the same procedure was used for leaching the reaction compound.
• the titanium metal obtained indicated a Brinel hardness of 145 and 0.0136 percent of hydrogen content.
• EXAMPLE V For the purpose of comparison the reaction was carried out by the same procedure as described in Example I with the only exception that the reaction temperature was maintained in the range of 800 to 780 C. Otherwise, the same procedure was employed for leaching the reaction compound.
• the titanium metal obtained indicated a Brinell hardness of 117 and 0.0104 percent of hydrogen content.
• a process for the preparation of high purity, low hydrogen metallic titanium which comprises:

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Cited By (3)

• 1968
  • 1968-07-29 JP JP43053082A patent/JPS491370B1/ja active Pending
• 1969
  • 1969-07-25 US US845026A patent/US3669648A/en not_active Expired - Lifetime
  • 1969-07-28 GB GB3776569A patent/GB1264344A/en not_active Expired

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