DD222274A1 - METHOD FOR CLEANING AN ALUMINUM IRON-BASED CHLORINE PRODUCT - Google Patents

Abstract

The subject of the invention is a purification process for iron-containing chlorination products of aluminum, in particular for iron chloride-containing aluminum chloride. The goal of the invention is the complete elimination of the iron content of iron-containing chlorination products of aluminum in a technically simpler manner. The object of the invention is the development of a purification process with which a complete elimination of the iron content of iron-containing chlorination products of aluminum, taking advantage of the different thermal behavior of the complex compounds of AlCl3 or FeCl3 with SCl4, in a technically simpler manner is possible. According to the invention, iron chloride-containing AlCl 3 is reacted with excess solution of Cl 2 in S2Cl 2 at from 20 to 200 ° C., the sulfur-containing AlCl 3 adduct SCl (AlCl 4) is distilled off from the reaction mixture at from 210 to 220 ° C. and the distillate is optionally rectified. Advantageously, the sulfur-containing AlCl3 adduct SCI (AlCl4) is distilled off at 210 to 220 ° C. from the condensate of an aluminum raw material thermochlorinated with S2Cl.sub.2 / Cl.sub.2 mixture, and the distillate is optionally rectified.

Description

-2- 252 533

The known complex compounds of AICI ₃ or FeCl ₃ with SCI ₄ show a very different thermal behavior. When heated namely a mixture of the complex compounds SCI ₃ (AICI ₄₎ and SCI ₃ (FeCl ₄₎ at temperatures of about 200 ⁰ C, it separates the iron compound in SCI _2, Cl _2, and FeCl _3, which only slightly volatile at these temperatures, is (bp 319 ⁰ C), while the SCI ₃ (AICI ₄ ) under CI ₂ TAB cleavage in SCJ (AICI ₄ ) passes, which distills without decomposition. By repeated distillation or better rectification, it is possible to obtain a product in which iron compounds are no longer detectable. The resulting sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) can be reacted in a technically simple manner with sodium chloride to Natnümtetrachlqroaluminat or starting from this, according to Trud. chemi. ' i chemi. technologii (1970) 2, 201, into aluminum chloride, compounds which are directly applicable in AICI ₃ melt electrolysis.

embodiments

The invention will be explained in more detail by the following embodiments, but the invention is not limited to these examples. , '

Example 1: '

20g of a condensate of the chlorination of metakaolin with CCI ₄ + O ₂ at 800 ° C were boiled with a stoichiometric excess of S ₂ Cl ₂ + Cl ₂ for 2 h under reflux. After driving off the excess S ₂ Cl ₂ , the residual product was heated to 22O ⁰ C, with SCI distilled off (AICI ₄ ). While the starting condensate had a Fe: Al molar ratio of 1:10 (13.6% by mass of Fe ₂ O _3, based on the oxide mixture), this ratio after distillation three times was 1: 453 (0.35% Fe ₂ O ₃ on oxide mixture). .

Example 2:. .

20g of a Kondensats.erhalten Thermochlorierung by a mixture of 95 wt .-% Al ₂ O ₃ and 5 wt .-% Fe ₂ O ₃ with S ₂ Cl ₂ + Cl ₂ are distilled in a glass apparatus. While the Fe: Al molar ratio in the resulting starting condensate was 1: 10.6 (12.9% by weight of Fe ₂ Oe ez., On oxide mixture), the corresponding ratio after distillation was 1: 370 (0.42 Ma % Fe ₂ O _3, based on oxide mixture).

Example 3:

20ig of the condensate from the chlorination of metakaolin with S ₂ Cl ₂ + Cl ₂ were heated to 220 ⁰ C, whereby distilled off SCI (AICI ₄ ). While the starting material had a Fe: Al ratio of 1: 100 (1.2% by weight of Fe ₂ O _3, based on oxide mixture), this ratio in the product distilled twice was only 1: 308 (0.51% Fe ₂ O _3, based on oxide mixture).

Example 4:;

95.1 g of SCI ₃ (AICI ₄ ) and 3.2 g SCI ₃ (FeCl ₄ ) were mixed and the mixture was heated to about 23O ⁰ C, the volatile component was distilled off. In the starting mixture, the molar ratio of Fe: Al = 1: 32.6 (4.6% by mass of Fe ₂ O _3, based on the oxide mixture), but after three times of distillation, 1: 123 (1.3% by weight of Fe ₂ O) ₃ with respect to oxide mixture).

Example 5:

117 g SCI ₃ (AICi ₄ ) and 2.4 g SCI ₃ (FeCl ₄ ) (Fe: Al = 1: 5.45, 22.4 mass% Fe ₂ O ₃ with respect to oxide mixture) were mixed and the mixture was treated as in Example 4, but the volatile component driven via a distillation column. After distilling twice, the Fe: Al ratio was 1: 6000 (0.03% Fe ₂ O ₃ relative to the oxide mixture), after three times of distillation no more iron was detectable by means of the rhodanide reaction.

Claims (4)

-1- 252 533 Invention claims: 1. A process for purifying an iron-containing chlorination product of aluminum, in particular iron chloride-containing aluminum chloride, characterized by reacting iron chloride-containing aluminum chloride with an excess solution of chlorine in Dischwefelchlorid at a temperature between 20 ° and 200 ⁰ C, preferably at 137 ° G, from the reaction mixture, after volatilization of the excess Dischwefelchlorids and chlorine, the sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) distilled off at a temperature between 210 ° and 22O ⁰ C and the distillate optionally rectified. , 2. The method according to item 1, characterized in that a condensate of the Thermochlorierungvon aluminum raw materials, optionally after the removal of silicon tetrachloride and titanium tetrachloride, with an excess solution of chlorine in Dischwefelchlorid at a temperature between 20 ° and 200 ⁰ C, preferably at 137 ° C, reacted from the reaction mixture, after evaporation of the excess Dischwefelchlorids and chlorine, the sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) distilled off at a temperature between 210 ° and 220 ° C and the distillate optionally rectified. 3. The method according to item 1, characterized in that the sulfuric aluminum chloride adduct SCI (AICI ₄ ) from the condensate of a Dischwefelchlorid / chlorine mixture thermochlorierten Alumihiumrohstoffes, optionally after the removal of silicon tetrachloride and titanium tetrachloride, at a temperature between ' Distilled off at 210 ° and 220 ° and the distillate optionally rectified. 4. The method according to item 1, characterized in that a mixture of sulfur-containing iron chloride adduct SCI ₃ (FeCl ₄ ) and sulfur-containing aluminum chloride adduct SCI ₃ (AICI ₄ ) heated to a temperature between 210 ° and 220 ° C, in this Temperature distilled off the sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) and the distillate optionally rectified. Field of application of the invention The invention relates to a process for purifying an iron-containing chlorination product of aluminum, in particular of iron chloride-containing aluminum chloride. The product purified according to the invention can be used, for example, for AICI ₃ melt electrolysis. , Characterization of the known technical solutions In the chlorination of primary or secondary aluminum raw materials, eg. B. poor Bauxites, clays, kaolins, 'Kraftwerksaschen fall, in addition to anhydrous AICI ₃ also SrCI ₄ , TiCl ₄ and FeCl ₃ , the latter is a very difficult separable from aluminum chloride impurity, but on the other hand must be completely eliminated when the recovered AICI _{3 is} to be used for Schmelzflußelektrolyse for the production of aluminum. The difficulties in obtaining a low-iron aluminum chloride are primarily due to the fact that AICI ₃ and FeCl _{3 form} a gas complex AIFeCI ₆ , which makes a separation of the two chlorides by sublimation very difficult. There are known a large number of methods which have the goal of producing a Fe-free AICI ₃ , such as. B. sublimation of the crude AICI ₃ from an AICIs / alkali metal chloride melt (DD-OS 2.702.413), the reduction of FeCl ₃ to less volatile FeCl ₂ or to iron by means of metallic aluminum (R.Weber, Ann. Phys. Chem. 4th R., Poggendorf, 13 (1858) 269; DP 502884) or gaseous hydrogen (AS 2.261.941). All of these methods have certain disadvantages, such as handling a very corrosive molten salt at relatively high temperatures, the use of purest aluminum or of dangerously explosive hydrogen. ' Object of the invention The aim of the invention is to completely eliminate the iron content of iron-containing chlorination products of aluminum, iris specific iron chloride-containing aluminum chlorides in a technically simpler manner. The technical problem which is solved by the invention The invention has for its object to develop a purification process, with a complete elimination of the iron content of iron-containing chlorination of aluminum, especially iron chloride-containing aluminum chloride, taking advantage of the different thermal behavior of the complex compounds of AICI ₃ or FeCl ₃ with SCI ₄ , in technically simpler manner is possible. Features of the invention A process has been found for purifying an iron-containing chlorination product of aluminum, in particular iron chloride-containing aluminum chloride. This process is characterized by reacting iron chloride-containing aluminum chloride with an excess solution of chlorine in disulphuric chloride at a temperature between 20 ° and 200 ° C, preferably at 137 ° C, from the reaction mixture, after volatilizing the excess disulphuric chloride and chlorine Sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) distilled off at a temperature between 210 ° and 220 ⁰ C and the distillate optionally rectified. It is also possible to react a condensate for the thermochlorination of aluminum raw materials, optionally after the removal of silicon tetrachloride and titanium tetrachloride, with an excess solution of chlorine in disulphuric chloride at a temperature between 20 ° and 200 ° C, preferably at 137 ° C. From the reaction mixture, after volatilization of the excess Dischwefelcrilorids and chlorine, the sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) in a. Distilled temperature between 210 ° and 220 ° C and the distillate optionally rectified. The process according to the invention is particularly advantageous when a condensate of an aluminum raw material which has already been thermochlorinated with a disulphuric chloride / chlorine mixture is present. From this condensate, optionally after the removal of silicon tetrachloride and titanium tetrachloride, the sulfur-containing aluminum chloride adduct SCI (AICI ₄ ) distilled off at a temperature between 210 ° and 22O ⁰ C and the distillate optionally rectified.