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Patented Oct. 26, 1937 2,097,064 UNITED STATES PATENT oFF-ics PROCESS FOR THE MANUFACTURE .OF HYDRQCYANIC ACID Emil Hene, London, England No Drawing. Application June 19, 1934, Serial No. 731,289. In Germany June 10, 1933 5 Claims. The invention relates. to the manufacture of hydrocyanic acid. It is known to produce alkali (Cl. 23—151) heated at a temperature of about 350° 0., where upon the temperature is raised to about 500° 0. cyanide compounds by heating potassium sulpho cyanide with zinc powder. But this process is 5 slow and the output of the acid is very insuf? cient. The process must be also conducted at a high temperature of over 900° C. These disadvantages are obviated by the in vention, which comprises subjecting a mixture 10 of one of the class of reversibly convertible com pounds consisting of thiourea or its derivatives, for instance, ammonium sulphocyanide with ?nely divided copper to a two staged heating treatment. In the ?rst stage of the process 15 the mixture is rapidly heated to a temperature of about 200-400° C. preferably to about 360° C. and in the second stage of the process the tem perature is increased to about 600° C. Instead of copper also copper alloys may be used. If thiourea is employed the conversion takes place essentially according to the following equation: Example 1.5 parts thiourea are mixed with 2.6 parts ?nely divided copper bronze; 0.5 part infusorial silica are added; the mixture is preferably under introduction of air heated to about 360° C. for about 45 minutes; the temperature is then slowly raised to about 600° C. 10 The gases escaping from the reaction contain HCN, NH3 and a small quantity of CS2. To obtain pure I-ICN the gases are passed through a rotary drum which is charged with a mixture of ammonium sulfate and concentrated 15 sulphuric acid and heated to a temperature of 80-100" C. If this process is conducted accord ing to the counter-current system, at one end of the drum the dry ammonium sulfate and at the other end the ammonium-free hydrocyanic‘ 20 acid are discharged. The CS2 may be removed in the usual manner through lead carbonate, ammonium sulphite or bisulphite. If ammonium sulphocyanide is used, the fol lowing reaction takes place: The quicker the temperature range of between 200-300" C. is reached in the ?rst stage of the process, the better is the yield of HCN. The tem perature should, therefore, be raised at a rate of at least 50° C. per minute. The output of HCN may be further improved by the addition of paraffin or substances con taining the same, for instance, bitumen, petro leum, etc. to the initial mixture. If the metals or alloys melt at the reaction temperature, they may be employed in an atom 40 ized condition; or the thiourea or ammonium sulphocyanide may be sprayed upon the surface of the molten charge, whereby excellent condi tions of reaction are obtained. As in the process essentially CuzS is formed the copper can be 45 easily recovered in the ?nely divided state by The invention allows a very economical pro duction of I-ICN from nitrogenous lime as simple methods are known to convert the same into 35 thiourea. A further particular advantage is gained there by insofar as the thiourea, which is produced in this manner, contains nitrogenous substances, which are made use of in the production of the HCN. As the HON resulting from this process can be easily converted into ferrocyanic corn~ pounds or sodiumcyanide, the invention affords a simple way, to obtain highly valuable nitrogen containing compounds from cheap nitrogenous, lime. The dry ammonium sulfate obtained at roasting and reducing the residues of the process. the same time forms a cheap basis for the manu The copper or the copper alloys may be also precipitated in the known manner on inert car facture of other ammonium salts. Copper and aluminum have been found to be suitable materials for the apparatus to be used for carrying out this process. What I claim is:— riers, for instance, silica gel. 50 The initial mixture may be employed in the‘ 25 shape of briquettes or tablets. The residues of this process consist essentially of CuzS, which by roasting and reduction is converted into ?nely divided copper. This con version may take place in the same apparatus, 30 where the production of the HON was carried out. The invention can be put into practise in the following manner:— Thiourea or ammonium sulphocyanide is sprayed on ?nely divided copper; paraf?n, pe troleum or bitumen are added and the mixture 5 01 is charged into a rotary furnace. It is then 45 1. The process for manufacturing hydrocyanic acid, which consists in rapidly heating in a ?rst phase of the process a mixture of one of the class of reversibly convertible compounds con 55 2 2,097,064 sisting of thiourea and ammonium sulphocyanide with ?nely divided copper up to a temperature ranging between 200° C. and 400° C. and‘ slowly 4. The process for manufacturing hydrocyanic acid, which consists in rapidly heating in the increasing in the second phase of the process the temperature to about 600° C. 2. The process for manufacturing hydrocyanic acid, according to claim 1, which consists in ?rst phase of the process a mixture of thiourea with ?nely divided copper up to a temperature of about 350° C., slowly increasing in a second phase the temperature up to about 600° 0., and regenerating the copper, which is contained in heating the mixture in the ?rst phase of the the residue of the reaction by roasting and re process to a temperature of about 350° C. 3. The process for manufacturing hydrocyanic 10 acid, which consists in rapidly heating in a ?rst phase of the process a mixture of one of ‘the class of reversibly convertible compounds con sisting of thiourea and ammonium sulphocyanide 15 with ?nely distributed copper deposited on an inert carrier up to a temperature between 200° C. and 400° C. and slowly increasing in the second phase of the process the temperature up to about 600° C. duction. , 5. The process for manufacturing hydrocyanic acid, which consists in rapidly heating in the ?rst phase of the process a mixture of ammonium sulphocyanide with ?nely divided copper up to _a temperature of about 350° C., slowly increas ing in a second phase the temperature up to 15 about 600° C., and regenerating the copper, which is contained in the residue of the reaction by roasting and reduction. EMIL HENE.