PROCESS FOR SIMULTANEOUSLY PREPARING ANHYDROUS ALUMINUM

CHLORIDE AND ZINC

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to a process for simultaneously preparing anhydrous aluminum chloride and zinc. More particularly, the present invention relates to a process for preparing anhydrous aluminum chloride which comprise mixing zinc chloride with aluminum metal at an equivalent ratio, and recovering the anhydrous aluminum chloride by cooling and condensing the vaporous aluminum chloride which is sublimated at a temperature of 183 ^° C when to heat the said mixture; and simultaneously separating and recovering zinc, which is melted at a temperature of 420 ^° C, by the difference of gravity.

DESCRIPTION OF THE PRIOR ART

Anhydrous aluminum chloride has been used as a catalyst for cracking process of petroleum, Friedel-Craft Reaction, etc., and the hexa hydrate has been used for refining wool, an antiseptic for wood, an additive for dye, petroleum refining process, paper manufacturing, paint, pigments, printing ink, etc.; and zinc metal is used at a large amount for steel plating, pipe plating, die-casting, copper-alloy, etc.

Conventionally, the various methods of production of anhydrous aluminum chloride have been known, and the methods thereof are classified generally as follows, for example, a method which reacting aluminum metal with chlorine at a high temperature; a method which reacting aluminum metal with hydrochloride gas at a high temperature; a method which reacting alumina or alumina-containing substance such as bauxite with carbon monoxide and chlorine or phosgene; a method thereof by reacting alumina or alumina-

containing substance with chlorine under the present of carbon, etc.

Among the above methods, a method of production of anhydrous aluminum chloride, which comprises by reacting aluminum metal with chlorine or hydrochloride gas at a high temperature is generally employed in the industrial scale, and more specifically, the said method comprises blowing chlorine gas into the melted aluminum and cooling the sublimated aluminum chloride to obtain it in a powder shape or massive state. However, in order to obtain the raw aluminum metal, it is necessary to melt alumina in the presence of a flux thereof around 960 °C or more, and subsequently subject to electrolysis it, thereby causing the method to be required much higher cost. In order to remove the said defect, many methods have been proposed, for example, a process for preparing anhydrous aluminum chloride which comprises by reacting alumina with chlorinating agent in the salt- melted bath containing alkali metal or alkali earth metal halide at the presence of reducing agent such as carbon (Japanese Patent Publication No. 293/1989), a process therefor which comprises by reacting oxide of aluminum with chlorinated hydrocarbon without a catalyst at a high temperature (Japanese Patent Publication No. 54286/1988); a process therefor which comprises sintering the mixture of raw material composed of aluminum- containing fine particle, carbon-containing fine particle and binder, and chlorinating the resulted sintered mixture by utilizing gaseous oxygen-containing chlorine (Japanese Patent Publication No. 1655/1990); and also a process for enhancing the purity of obtained aluminum chloride (Japanese Patent Publication No. 38287/1978, Japanese

Patent Publication No. 7640/1976, Japanese Patent Publication No. 27838/1975, Japanese Patent Publication No. 5526/1984, etc.).

The above methods have drawbacks that uses the expensive raw material, or occurs simultaneously carbon monoxide and carbon dioxide gas in the course of preparing anhydrous aluminum chloride when reacting aluminum oxide (bauxite) with reducing agent, carbon at the high temperature, and these methods require the step of cooling the gaseous complex material and also step of refining aluminum chloride in order to obtain

high purity aluminum chloride.

And, zinc metal has been conventionally prepared by dry preparation method and wet preparation method.

Accordingly, development ofthe improved method of preparation of aluminum chloride with high purity and low cost, being as solved the above defects, has been desired.

The present inventors have undertaken earnest studies in order to solve the above problems in the prior art, and as a result, have found that aluminum chloride and zinc can be easily obtained by reacting zinc chloride with aluminum , which led to the completion ofthe invention.

SUMMARY OF THE INVENTION

Accordingly, an object ofthe present invention is to provide a novel method of preparation of aluminum chloride and zinc simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a front view of an apparatus for simultaneously preparing aluminum chloride and zinc in accordance with the present invention.

Figure 2 is an enlarged front view of a shelf embedded with aluminum granules mounted inside the refining tower ofthe apparatus shown Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the detailed description of preferred embodiments, the same numerals will be utilized to designate the same parts in the respective views. Figure 1 is a front view ofthe apparatus for simultaneously preparing aluminum chloride and zinc, which consists ofthe reactor 1. the multi-stage refining tower 6 and the rotating tube 9.

The reactor is equipped with inlet 3 for introducing the molten zinc chloride, hopper 4 for introducing aluminum powder or aluminum particles, an agitator 2 And the bottom of the reactor 1 has the drain pipe 5 for draining the formed molten zinc metal

The refining tower has the reticulated shape - shelves 7 embedded with aluminum granules 8 The vaporous aluminum chloride and zinc chloride generated from the reactor 1 are contacted with aluminum granules on the shelves, thereby the unreacted mist zinc chloride from the reactor reacting with aluminum in this tower

The obtained aluminum chloride containing a trace amount of zinc chloride from the refining tower is passed the rotating tube 9, wherein aluminum granules are embedded at an amount of about two third (2/3) ofthe volume of the rotating pipe

Figure 2 is the shelves part 7 of Figure 1

The above apparatus are provided herein for purposes of illustration only and are not intended to be limiting the present invention

The present invention provides a method for producing aluminum chloride and zinc which comprises introducing molten anhydrous zinc chloride into the melt - bath (reactor) having an agitator 2, and adding, while agitating, aluminum powder or melted aluminum which is reacted with zinc chloride

The chemical formula ofthe present invention can be shown as follows.

3ZnCl ₂ + 2A1 → 3Zn + 2A1CU

To explain it more specifically, the molten aluminum or aluminum powder is added, while agitating , to a high purity zinc chloride in molten state in the reactor, maintaining the average temperature of 420 to 500 ^° C , whereby aluminum chloride being sublimated at 183 °C or more, and then the sublimated aluminum chloride is subjected to be cooled and desublimated to produce aluminum chloride in power or flake shape (crystal or prismatic

state).

And also, zinc metal is settled down on the bottom ofthe zinc chloride melt in the reactor by the difference of specific gravity and the resulted zinc metal is drained through drain pipe to a mold and then solidified to give a desired product.

According to the present invention, the high-value zinc metal and aluminum chloride can be obtained by reaction of zinc chloride and the molten aluminum metal, especially zinc metal is obtained at the rate of 3.6 times in weight with regard to an amount of aluminum metal being reacted. Accordingly, the present invention is a useful melt- metathesis reaction economically to obtain aluminum chloride and zinc metal

The reaction is preferably carried out in the aforementioned temperature range. It is not proper to carry out the reaction more than 740 ^° C , since zinc chloride is vaporized at the said temperature to contaminate the sublimated aluminum chloride, and also below 420 ^° C which is fusing temperature of zinc, it is difficult to obtain zinc continuously. In view of such property of the reaction material and resulting material, the reaction temperature is preferably 420 to 500 ^° C , more preferably 450 to 480 °C .

The purity of zinc metal and aluminum chloride depend on the purity ofthe raw material, zinc chloride and aluminum. Especially, when pure zinc chloride containing not more than 100 ppm of iron, nickel, cadmium, etc., or refined zinc chloride being eliminated the above metal components is used, the zinc is produced with high purity, i.e. 99% to 99.8% purity.

And, the pure aluminum chloride being sublimated is subjected to be guided to a multi-stage contact refining tower 6, in which vaporized zinc chloride being accompanied, maintaining vapor temperature of 185 to 80 ^° C , is mostly converted to zinc and aluminum chloride by contact with aluminum granules or particles, and then in the next step, vaporous aluminum chloride is passed through the rotating tube 9 being embedded

with aluminum particles (5 to 10 mm thick) to react zinc chloride being present at a trace amount, thereby zinc chloride being eliminated as being converted to zinc metal, and then gaseous aluminum chloride with high purity is cooled to give as powder or prismatic shape

It is possible to accomplish the present invention by the batch process, but it is very difficult to control the reaction rate of zinc chloride and aluminum of reactant by the batch process And therefore, it is preferable to carry out the present invention by a continuous process That is to say, molten zinc chloride and molten aluminum metal are continuous fed to the reactor during the process ofthe reaction, thereby the productivity of zinc being obtained more than 10 to 100 ton per day from one reactor(diameter 4 m, height 3 m) having a refining tower and the rotating pipe (diameter 1 2 m, length 2 m)

In the conventional methods, poisonous chlorine or hydrochloride gas has been used for obtaining aluminum chloride, but in the present invention, such poisonous gas is not used, and moreover zinc scrap, etc is reacted with hydrochloric acid to form the pure zinc chloride and the resulted zinc chloride is reacted with aluminum powder or molten aluminum which is obtained from aluminum metal or aluminum scrap, at a melt state to produce aluminum chloride and zinc metal with high purity Such a method is very economical, since the present process is proceeded to be completed at a relatively low temperature, compared to the conventional methods

EXAMPLES

More detail descriptions are explained by the following examples In the examples, "%" means % by weight

Example 1

To the Erlenmeyer flask having the condenser, 200 g of purified zinc chloride and

average temperature of 480 °C for 40 minutes to collect 130 g (yield: 99.65%) ofthe pure aluminum chloride at the condenser and also to obtain 92.16 g(96.07%) of zinc metal from the bottom ofthe flask. In this reaction, what the yield of zinc was 96.07% means the loss due to unreaction and un-progress ofthe reactant by the batch process.

Example 2

To the Erlenmeyer flask having the condenser, 210.5 g ofthe molten liquid consisted of 95% of zinc chloride, 2% of iron, 1% of lead and 2% of zinc oxide, and 26.4 g of aluminum powder were added, and then the reactor was heated at an average temperature of 480 ^° C for 50 minutes to obtain 97.4 g of metal consisted of 98.5% of zinc metal, 1% of iron, and 0.5% lead.

From the above, it is proved that impurities such as chlorides of iron, cadmium, lead, etc. in the molten liquid of zinc chloride are reduced simultaneously to form alloy of zinc, thereby such impurities causing to lower the purity of product. And therefore, it is necessary to purify the raw material, zinc chloride before being introduced to the reactor, in order to obtain the high pure product.

Example 3

To the Erlenmeyer flask having the condenser, 200 g of purified zinc chloride and 27.2 g of aluminum scrap (purity : 97%) which was obtained from aluminum can were added, and then the flask was heated at an average temperature of 480 °C for 40 minutes to complete the reaction, and as a result, 128.7 g of zinc metal being consisted of 97.5% Zn, 0.5% Fe, and 1% Si, and 93 g of aluminum chloride.

Example 4

To the Erlenmeyer flask of 500 mi, 200 g of zinc chloride and 26.4 g of aluminum powder were added, while heating 480 ^° C and as a result of analysis of vaporous

aluminum chloride being produced, about below 3% zinc chloride was contaminated therein. In order to eliminate zinc chloride in the vaporous aluminum chloride, the resulting vaporous aluminum chloride was passed through the pipe (diameter 30 mm, length lm) embedded with aluminum granules (diameter 5 to 10 mm) at an amount of two third(2/3) volume ofthe pipe, maintaining the average temperature of 380 °C, and then passed vaporous aluminum chloride was subjected to be cooled to give 130.44 g of crystal aluminum chloride. As a result of analysis of obtained aluminum chloride, the purity thereof was 99.1% and the contained zinc chloride therein was 0.02%.

Example 5

To the Erlenmeyer flask of 500 m , 200 g of zinc chloride and 40 g of aluminum powder were added, and the flask was heated until the reaction is completed to give zinc which is alloyed with a relatively large amount of aluminum. The resulted aluminum alloy was added to pure molten zinc chloride in order to react aluminum in the alloy continuously, thereby obtaining pure zinc (99.3%).

From this experiment, it is proved that when aluminum and zinc alloy are also reacted with zinc chloride at the sufficient reaction temperature, aluminum in the alloy is selectively reacted.

As apparent in the above examples, the vaporous zinc chloride being contaminated with vaporous aluminum chloride simultaneously is reacted with aluminum granules or particles and subsequently, zinc chloride is converted to zinc powder, which is settled down on the reactor, thereby pure aluminum chloride can be obtained.

And also, the refined zinc chloride being used leads to a production ofthe pure zinc metal. Since aluminum metal is easily become an alloy with zinc metal, it is preferable to feed aluminum power to become an equivalent amount to the molten zinc chloride, which is present as a little excess, in the reactor, in order to avoid formation of alloy. And such a

product can be obtained without any further refining process

INDUSTRIAL APPLICABILITY

A process for simultaneously preparing anhydrous aluminum chloride and zinc according to the present invention provides an industrially useful and economical one for obtaining the pure final product without further refining process