DE1667698C - Process for chlorinating hard metal-containing materials - Google Patents

Description

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The invention relates to a process for chlorinating reaction products carried out by distillation hard metal-containing materials, which is the predominant disadvantage,

lowing part of the hard metals tungsten carbide, the reaction products are used to clean them Tantalum carbide, niobium carbide and / or titanium carbide and distilled, so it is more advantageous if the chlorinated to a lesser extent from the binding metals cobalt 3 tungsten compound in the form of tungsten hexachlo-

and / or nickel. rids instead of in the form of tungsten oxychloride,

It is known that hard metal waste can be recovered because in this case the chlorides obtained can be more easily recovered

to chlorinate valuable metals. Will clean though. This is particularly important when considering

during the chlorination only chlorine is added, so the boiling point compiled below

After a while the implementation of the chlorides in question comes to a standstill:

stood because on the carbide pieces or -ab- WOCl SdD 227 ° C

precipitate carbon deposits, so that 'the chlorine and the la.C \ * Sdp 239 ° c'

Hard metal no longer in contact with each other Nbcf Sdo 254 ° c'und

can come. It is also known that on _wr , ⁵ cHn -M7 ° r

carbon deposited in the hard metal waste by 15 * ^p '

Remove oxygen supply. This procedure The compilation shows that the

has the disadvantage, however, that here in the boiling point difference between tungsten oxychloride and

undesirably, the various oxy-tantalum pentachloride is only 12 ° C, while

can form chlorides of the hard metals mentioned. the boiling points of niobium pentachloride and tungsten

The separation and work-up of the individual ao hexachloride are 93 ° C apart. Reaction products cause considerable difficulties in carrying out the process

problems. of the invention chlorine and carbon dioxide as a mixture

The invention is based on the object of developing a supply so that a certain amount of tungsten for chlorinating hard metal-containing materials ramoxychloride (WOCl ₄ ), but no WO ₁ Cl ,, tantalum of the composition mentioned is developed, with as oxychloride (TaOQ ₃ ) or Niobium oxychloride (NbOCl ₃ ). its implementation means a permanent deposition. This means, as already mentioned, compared to the process of free carbon on the hard-known processes to be chlorinated, in which oxygen is greatly reduced or completely avoided in converting the carbon into a gaseous state for converting metal waste. used has a significant advantage. In the

According to the invention, the object is to carry out the method according to the invention

drive of the type mentioned at the beginning is solved, but the amount of the resulting WoIf-

that you reduce carbon dioxide ramoxychlorids (WOCl ₄ ) during the chlorination, if the

feeds. the reaction vessel containing hard metal scraps the

By supplying carbon dioxide, chlorine and carbon dioxide are alternately supplied. The method of the invention achieves that the in the 35 The method according to the invention is suitable in Hard metal scraps contained cairbid carbon in the neter manner at elevated temperatures, in particular Do not run the implementation on the hard metal at temperatures above 70O ⁰ C, preferably at a

fall off as free carbon deposits, but at a temperature of about 100O ⁰ C, carried out,

a gaseous state is transferred. The response time can be very different. she

in this way there is no danger that the chlorination 40 plays, however, to a successful implementation of the

the carbide waste is prevented or inhibited. Procedure does not play a decisive role.

In the known process for removing at said temperatures of the carbon end deposited free carbon is by supplying material in accordance with the reaction equation: difficulties arising from oxygen, namely _co, ~ _ ^ * rn the formation of 'Öxychloriden such as 45 *

Tungsten oxychloride * $ WOCIJ, (WO ₁ Cl,), tantalum oxy- converted into the gaseous state. In this

chloride (TaOCl ₈ ) and niobium oxychloride (NbOCl,) in addition to connection it should be noted that pure

the pure chlorides tungsten tachloride, tungsten carbon dioxide at the high temperatures used

hexachloride, tantalum pentachloride, niobium pentachloride temperatures the hard metals neither attack nor oxidize,

and titanium tetrachloride are carried out 5 °. Furthermore, the carbon dioxide does not react either

of the process according to the invention also in one of the chlorides that have already formed and condensed,

solved in a fan manner, since the formation of the oxychloride

insufficient oxygen is made available. amount of carbon dioxide supplied to the vessel

An increase in the proportion of by-products, preferably, based on 1 kg of hard metal, 0.05 to

as is the case with the known methods, 55 1.0, preferably 0.2 to 0.4 kg.

is particularly suitable for the subsequent cleaning of the If with alternating supply of chlorine and

Reaction products disadvantageous, The purification of the carbon dioxide is sufficiently short feed-in period Reaction products is made highly difficult to choose, so the scraps of cemented carbide act as

the thermal buffer compounds obtained as by-products, with the during the exothermic

WOjCI, and TaOCI _{4 are} unstable and, according to the chlorination reaction, heat developed during the other

decompose according to the following equations: closing, endothermic gas formation reaction reacts

2 WO-Cl- ~ * WOCl, 4- WO tone-accelerating,

and ^{WW | W1} * ^ ^wu * - '«^ ^wu » About a mixture of carbon dioxide and chlorine

^To prevent {TnOfI ~ * τ "ο 4-1 Tnfi, you may optionally each be-

5 Tauu, - + Ta ₁ O, + 3 Tau » _6% ^ _n ^ _{gjJ {feftnten Chjof} . _odef carbon dioxide supply

The in the known processes also as a small amount of inert gas, for example nitrogen, By-product NbOCIi is stable, supply, This is done, for example, so that one

sublimates, however, which in a cleaning process is first chlorine, then inert gas, then carbon

Lendioxyd and again supplies inert gas. This order the gas supply can be repeated as often as desired. In the event that between the separate feed an inert gas is fed into the reaction vessel for each of the individual reactants, this drives off on the one hand, both the gaseous chlorine still present from the last reaction stage and that during Chlorides formed in this reaction stage or, on the other hand, that in the next reaction stage Carbon monoxide formed or carbon dioxide still in the reaction vessel. On the other hand, can the carbon monoxide formed, mixed with any carbon dioxide that is still present, is also diverted separately so that the gaseous chlorides are obtained undiluted.

The following examples are intended to illustrate the invention in more detail.

Example I.

A reaction vessel made of quartz was charged with 6.3 kg of tungsten, tantalum and niobium carbide and hard metal waste containing cobalt. After heating the Reaktiunsgefäßes on IQOO ⁰ C chlorine, Stickstof and carbon dioxide were fed to this alternately. The gases in question were fed in in such a way that initially 10 minutes la % 25 g / min. Chlorine, then 2 liters / min for 1 minute. Nitrogen, finally 5.7 liters / mm 2 for 10 minutes. Carbon dioxide, then again for 1 minute 2 liters / min. Nitrogen, etc. were introduced. During the experiment, 20.6 kg of chlorine and 21 kg of hard metal waste were added.

After 16 hours of chlorination, the amount of free carbon was based on the remaining amount Carbide waste, 0.2%. The remaining amount of cemented carbide scrap was 4.4 kg. With one afterwards Analysis carried out, it was found that the amount of oxychloride, based on the total amount of obtained chlorides, was below 3%.

Example II

In a reaction vessel made of quartz, 23 kg of tungsten carbide and cobalt-containing hard metal scraps were chlorinated. The chlorine and carbon dioxide were then added in such a way that initially chlorine and carbon dioxide were added for 10 minutes - the amount of carbon dioxide here was 0.7% of the amount usually required to convert all the deposited carbon into a gaseous state -, Then carbon dioxide alone for 10 minutes - the amount of carbon dioxide was so great that a total excess of 80% was reached - finally chlorine and carbon dioxide for 10 minutes - the amount of carbon dioxide was 0.7% of the theoretically required amount - uiwv were introduced .

After the end of the chlorination, ie after a reaction time of about half an hour, 25 g of free carbon could still be detected. This residual carbon content was 2% of the total carbon bound in the hard metal waste. The remaining amount of waste was 5.4 kg. Analysis of the end product showed that 30% of the chlorides formed were obtained in the form of tungsten oxychloride (WOCl ₄ ) and the remainder as tungsten tachloride (WCl ₅ ).

Example IH

ίο In a reaction vessel made of quartz, tungsten carbide, tantalum carbide, niobium carbide, titanium carbide and cobalt were chlorinated at a temperature of 1000 ° C. In the present case, the chlorine was introduced not only into the waste itself, but also into the hot gaseous reaction products above the waste, so that the tungsten tachloride (WCI ₁ ) initially formed was converted into tungsten hexachloride (WCI,). The chlorine discharged into the waste was

ao per 2.4 moles of chlorine (Cl ₁ ) with 1 mole of carbon dioxide

mixed. After about 5 hours of implementation in Vessel residue detected amount of free carbon was insignificant.

An analysis of the chloride mixture obtained showed that

> 5 that it consisted of 23% tungsten oxychloride (WOCl ₄ ), 44% tungsten hexachloride (WCl,) and the remainder of tantalum pentachloride CTaCl ₅ ), _{niobium pentachloride (NbCl 5} ) and titanium tetrachloride (TiCl ₄ ).

Claims (7)

Patent claims: 1. Process for chlorinating hard metal-containing materials, which for the most part consist of the hard metals tungsten carbide, tantalum carbide, niobium carbide and / or titanium carbide and to a lesser extent Part from the bin '* metals cobalt and / or nickel, characterized that carbon dioxide is added during the chlorination. 2. The method according to claim 1, characterized in that that, based on 1 kg of hard metal, 0.05 to 1.0 kg, preferably 0.2 to 0.4 kg of carbon dioxide feeds. 3. The method according to claim 1 or 2, characterized in that alternating pure carbon Lendioxyd and pure chlorine gas supplies. 4. The method according to any one of claims 1 to 3, characterized in that between the Carbon dioxide and chlorine gas supply an inert gas supplies. 5. The method according to claim 4, characterized in that that nitrogen is used as the inert gas. 6. The method according to claim 1 or 2, characterized characterized in that the carbon dioxide is supplied as a mixture with the chlorine gas. 7. The method according to any one of claims 1 to 6, characterized in that temperature of fiber 700 ^e C, preferably at 1000 ⁰ C, operating at a Tem ·.