BARTOLO J (BR)
BARTOLO J (BR)
| US3736239A | 1973-05-29 | |||
| JPS4510905B1 | ||||
| US2845330A | 1958-07-29 | |||
| US1614523A | 1927-01-18 | |||
| JPS50656A | 1975-01-07 | |||
| SU528265A1 | 1976-09-15 |
| 1. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA¬ NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALSRepresented by a simple process to precipitate, recuperate and reuse the cyanide contained in the rinsing solutions which are lost in the conventional industrial methods of electrodeposi^ tion of metals.. The electroplating industry demands an eco¬ nomical and practical system for the rinsing solution treat ment. It is included in the technical sector of Electroche mistry, specifically the recuperation of residual products in the rinsing solutions. It is characteristic in that, by the addition of chemical products, the soluble cyanides con¬ tained in the rinsing solutions are transformed by a chemi¬ cal reaction into insoluble cyanides f thus making possible the recuperation and reuse for industrial purposes. This re_ cuperation must occur by the conventional processes of depo¬ sition or filtration. |
| 2. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA¬ NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, according to Claim 1, characterized by the full precipitation of insol. uble cyanides in the rinsing solutions, coupled with the met als of the residual cyanides to attempt the industrial recu¬ peration so that, according to the quantity of cyanide in the rinsing solution, there must be additions of adequate quantities of metallic salts which correspond to the metal coupled with the cyanide in the rinsing solution and the electrodeposition of metal dip. |
| 3. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA¬ NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, according to Claims 1 and 2, characterized by having all the cyanide contained in the water transformed into an insoluble salt, thus making possible the easy extraction from the rinsing solution via deposition or filtration, and that the precipi. tated metallic cyanide can be directly reused in the re spective dips after their rinse. The insoluble precipitate will be obtained in the pure form for reusage in the fil¬ ters or in the deposition tanks, after the rinsing water ■^URtALT CMPI "Y.'IPO has reached a density equal to 1. 000 or 0° Be ; under these conditions , the cyanide precipitate is separated from the other soluble components . |
| 4. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, accordin to Claims 1, 2 and 3, characterized by the addition of met allic salts, where the metals of the salts show an atomic weight over 60 and, if necessary, in conjunction with salts gases and/or acids, these alter, the valency of the metalli ions contained in the rinsing solutions and/or associated with salts and/or acids, to correct the water pH. |
| 5. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA¬ NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, accordin to Claims 1, 2, 3 and 4, characterized also by being used for the precipitation and recuperation of any cyanidric li quid bearing cyanides which has been used for the electrode position process of zinc, copper, cadmium, silver or gold and their alloys. |
| 6. | RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, accordin to Claims 1, 2, 3, 4 and 5, characterized by having a gen¬ eralized chemical formulation in which the symbol M rep¬ resents a metal with an atomic weight between 60 and 200, and the generic formula considered is presented thus: (M(CN)2 3 4)1,2'3~ + nMCl = nMCN M(CN)4~ + MS04 = nM(CN)2 OA '. |
Everyone in the trade knows that the treatment of cyanide bearing rinsing solutions is attained mainly through the p ' oi_ son -elimination process by destruction of the cyanide. Ano ' th er known process, the recycling, is based upon the evapora- tion of the solvent in the rinsing solutions, by using ener¬ gy to concentrate the fluid which will be re-used in the re¬ spective dips.
other processes are also known which use ion exchangers, involving high capital investment for equipment and the loss of chemical products through their destruction. c) DISCLOSURE OF THE INVENTION The process which is now proposed allows the total precipi¬ tation of the cyanides in the insoluble form, together wit the cyanide metals and their recuperation for industrial re-use. According to the amount of cyanide in the rinsing solutions adequate quantities of metallic salts shall be added; these will correspond to the metal associated with the cyanide i the rinsing solution and in the electroplating dip. As an example, the zinc sulphate and/or chloride for rinsing so¬ lutions of the cyanidric zinc dip, or else the copper sul- phate and/or chloride for the rinsing solution of the cya¬ nidric copper dip, associated with acid or alkaline salts which control the pH value of the rinsing solution and the valency of the metallic ions, according to the type of met- tal, thus obtaining a full transformation of all the free cyanide and cyanides associated in complex salts to a sim¬ ple metallic cyanide, insoluble in water with an adequate pH in the rinsing solutions, without releasing cyanidric gases. All the cyanide in the water is thus transformed into an insoluble salt, and may be removed from the rinsing solu¬ tion through deposition or filtration.
By using for each type of metal in the electrodeposition of metals process separate rinsing tanks without danger of in¬ termixing metals, the metallic cyanides precipitated by means of the proposed process, that is theRECUPERATION OF CYA NIDES FROM RINSING SOLUTIONS OF CYANIDRIC PROCESSES FOR ELEC¬ TRODEPOSITION OF METALS, maybe directly re-used in the re¬ spective dips after their rinsing (the insoluble precipi¬ tate) in the filters or by deposition with water, until the rinsing water attains a density of 1.000 or 0° Be, thus re¬ leasing the precipitated cyanide fromthe other soluble α-xηpσnent The same process presented may also be used for the precipi
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tation and/or recuperation of cyanide from any cyanidric li uid already used in the electroplating of zinc, cadmium, co£ per, silver, gold and their alloys.
The initial experiments have already demonstrated the sim- plicity Of the RECUPERATION OF CYANIDES FROM RINSING SOLU¬ TIONS OF CYANIDRIC PROCESSES FOR ELECTRODEPOSITION OFMETALS, where there is no need for epecialized technical personnel, nor special equipment; neither does it consume chemical prod ucts for later destruction. It reclaims efficiently the val- uable chemical products from the waters, where the value of the metallic salt used for the precipitation and recupera¬ tion is two to six times lower than the reclaimed material, e) BEST MODE OF CARRYING OUT THE INVENTION To demonstrate the technical and economic value of the proc- ess for RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYANIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS, it will be exemplified in two cases:
First case: Cyanidric zinc dip, with the following formulation: - 60 g/liter of zinc cyanide at Cr$ 130,00/kg = Cr$ 7,80 50 g/liter of sodium cyanide at Cr$ 100,00/kg = Cr$ 5,00 70 g/liter of caustic soda at Cr$ 18,00/kg = Cr$ ' 1,26
One liter of zinc dip Cr$ 13,06
When one liter of the zinc dip is flushed to the rinsing tank, the following materials are needed to precipitate the soluble cyanide and part of the sodium hydroxide (caustic so da) :
- 200 g of zinc sulphate at Cr$ 14,00/kg = Cr$ 2,80 The value of the recuperation and.precipitated material af- terwards is:
- 120 g of zinc cyanide at Cr$ 130,00/kg = Cr$ 15,60
16 g of zinc hydroxide at Cr$ 40,00/kg - Cr$ 0,64 Value of recuperated material Cr$ 16,24
This means that the value of the recuperated material is 5.8 time ' s the value of the material used for the recuperation. The water after this treatment presents no cyanides, no heav y metals and there remains only sodium sulphate and traces
( -f'MPI : ^__ o .Λ
of sodium hydroxide, which are easily neutralized.
Second case: Cyanidric copper dip, with the following formulation: Cr$
60g/liter of copper cyanide at Cr$ 180,00 pAg = 10,8 81g/liter of sodium cyanide at Cr$ 100,00 p/kg = 8,1
15g/liter of sodium hydroxide at Cr$ 18,00 p g =- 0,2 One liter of .copper dip = 19,1
Therefore, a liter of copper dip when flushed to the rinsin tank needs the following amount of materials to precipitate the soluble cyanide:
161 g of copper chloride at Cr$ 111,60 p/kg = Cr$ 17,9
The value of the recuperated and precipitated material will then be the following: 210 g of copper cyanide at Cr$ 180,00 p/kg = Cr$ 37,8 The value of the reclaimed material is therefore 2.1 times the value of the metallic salt used for the recuperation.
The water after the treatment has no cyanides and no heavy metals, and there remains only the sodium chloride, which i no problem for the water treatment. The two cases given above give a good demonstration of the technical and economic value of the RECUPERATION OF CYANIDE
FROM RINSING SOLUTIONS OF CYANIDRIC PROCESSES FOR ELECTRODE
OSITION OF METALS.
The traditional processes for the treatment of cyanide bear ring waters show the following values concerning the usage of chemical products for the destruction of the unreclaim- able cyanides:
First case: For one liter of zinc bath dip:
- 360 g of chloride = Cr$ 2,88 410 g of sodium carbonate = Cr$ 7,38
Total Cr$ 10,26
Second case: For one liter of copper dip:
- 430 g of chloride = Cr$ 3,44 490 g of sodium carbonate - Cr$ 8,82 Total Cr$ 12,26
These expenditures do not yet include the cost of filtering and separating the slurry, the capital investment for equi£ ment and the running expenses for storage of these residues in adequate locations. f) INDUSTRIAL APPLICABILITY
In these comparisons, the physical values are constant in¬ ternationally; -the values in money may show up in relation to the cost of the chemical products per country. The mone tary values must be considered for comparisons, and the approximate equivalent in Brazil of one United States Dol¬ lar is thirty cruzeiros: (1..00 = Cr$ 30,00). In most countries, the copper, the zinc, the cadmium, the silver, the gold and cyanides are imported materials, thus justifying avoidance of the loss of these products in the rinsing solutions in the electroplating industry.
The electroplating industry is up against problems con¬ cerning the compliance with the standards of public organs, which are responsible for the preservation and protection of the ecology. They demand an efficient and complete treat ment of the industrial effluent waste products.
The high toxicity of cyanides is well known and, therefore, the necessary and strict controls by public organs over the electroplating industry are well justified. The process for RECUPERATION OF CYANIDES FROM RINSING SOLU- TIONS OF CYANIDRIC PROCESSES FOR ELECTRODEPOSITION OF MET¬ ALS is thus the only one which allows the treatment of waste waters with cyanides with profit to the users through the recuperation of the material via visual control of the treatment, thus eliminating the necessity for high costing equipment, avoiding any aggression on ecology.
The RECUPERATION OF CYANIDES FROM RINSING SOLUTIONS OF CYA¬ NIDRIC PROCESSES FOR ELECTRODEPOSITION OF METALS may also be a technique which can be applied to sundry other pro¬ cesses of recuperation of cyanides, the importance of which for the chemical and electrochemical industries in all coun tries needs no discussion. The following four chemical formulae demonstrate the devel-
opment of the reactions of the insoluble copper cyanide with the potassium cyanide dissolved to form the complex salt of soluble copper cyanide, demonstrating furthermore how the complex soluble copper cyanide by the addition of copper chloride transforms itself into the insoluble cop¬ per cyanide at the rinsing solution treatment stage:
- 1) CuCN + KCN = K (Cu(CN) 2 )
- 2) K (Cu(CN) 2 ) + KCN = K 2 (Cu(CN) 3 )
- 3) K 2 (Cu(CN) 3 )
- 4) (Cu(CN) 2 3 4 ) nCuCN insoluble
In formula four, there would be no difficulty in exchanging the copper chloride for copper sulphate. By using the insoluble zinc cyanide with the sodium cyanide in the assembly of the zinc dips, we would obtain the solu¬ ble compex salt zinc cyanide which may be precipitated with zinc sulphate at the rinsing solution treatment stage ac¬ cording to the formulation: Zn(CN) 4 2" + Zn S0 4 = 2Zn (CN) 2 insoluble
The precipitation formulation may be generalized consid¬ ering as -M- the symbol of a metal, the atomic weight of which is between 60 and 200, thus allowing the objective of the recuperation of the cyanides and the respective metals in the rinsing solutions.
(M(CN) 2 3 4 ) 1 ' 2 ' 3 + nMCl = nMCN
M(CN) 2" + MS0 4 = nM(CN) 4 Δ
The technical and economic importance represented by the precipitation of cyanides from rinsing solutions from cya- nidric processes for electrodeposition of metals may, thus, be seen by the addition of metallic salts along with salts and/or acids to correct the pH value of the water and asso¬ ciated with salts, gases and/or acids to correct the valen¬ cy of metallic ions, when necessary.
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