Metal cyanides Copper cyanide

Cyanide Disinfectants SPA Sodium cyanide Copper cyanide Heat treatment of metal Coal distillation Electroplating Photographic Synthetic fibre Agriculture and horticulture Abattoirs Eood processing... 

Cyanide occurs most commonly as hydrogen cyanide in water, although it can also occur as the cyanide ion, alkali and alkaline earth metal cyanides (potassium cyanide, sodium cyanide, calcium cyanide), relatively stable metallocyanide complexes (ferricyanide complex [Fe(CN)6]-3), moderately stable metallocyanide complexes (complex nickel and copper cyanide), or easily decomposable metallocyanide complexes (zinc cyanide [Zn(CN)2], cadmium cyanide [Cd(CN)2]). Hydrogen cyanide and cyanide ion combined are commonly termed free cyanide. The environmental fate of these cyanide compounds varies widely (Callahan et al. 1979). 

Anodes. There are two types of anodes soluble and insoluble. Most electroplating baths use one or the other specifically however, a few baths use either or both. Chromic acid plating baths use insoluble anodes alkaline zinc cyanide baths use both noncyanide alkaline zincs may use either. Soluble anodes are designed to dissolve efficiendy with current flow and preferably, not to dissolve when the system is idle. A plating solution having the anode efficiency close to the cathode efficiency provides a balanced process that has fewer control problems and is less cosdy. If the anode efficiency is much greater than the cathode efficiency and there are only small solution losses, the dissolved metal concentration rises until at some time the bath has to be diluted back or the excess metal has to be reduced by some other means. If the anode efficiency is less than the cathode efficiency, the dissolved metal decreases, pH decreases, and eventually metal salt additions and other solution corrections are required. Based on the cost of metal, it is usually considerably more economical to plate from the anode rather than add metal salt. Copper cyanide, for example, costs about twice as much to add than to dissolve a comparable amount of copper anode. Additionally, the anion added with the metal salt may build up in the plating solution. 

Basic copper carbonate is essentially iasoluble ia water, but dissolves ia aqueous ammonia or alkaU metal cyanide solutions. It dissolves readily ia mineral acids and warm acetic acid to form the corresponding salt solution. 

For strike on nonferrous metals and a second strike on steel, first strike uses 1.5 g/L AgCN, 75—90 g/L KCN, and 10—15 g/L copper cyanide. 

Cyan-kalium, n. potassium cyanide, -kalium-losung, /. potassium cyanide solution, -ko-balt, m. cobalt cyanide, -kohlensaure, / cyanocarbonic acid. -kupfer, n. copper cyanide, -laugerei, -laugung, /. cyaniding. cyanidation. -losung, / cyanide solution, -metall, n. metallic methyl cyanide, -natrium, n. sodium cyanide. -platin, n. platinum cyanide. 

Many baths in which metal is reduced from complex anions (e.g. cyanide baths, stannate baths) give high throwing indices because both polarisation and cathode efficiency variation favour a low value of M. The cathode efficiency for a typical copper cyanide bath (40°C) was ... 

On ferrous metals immersion deposition in the copper sulphate bath produces non-adherent deposits, and a cyanide copper undercoat is therefore normally used. Where the use of a cyanide strike cannot be tolerated, an electroplated or immersion nickel deposit has been used . Additions of surface-active agents, often preceded by a sulphuric acid pickle containing the same compound, form the basis of recent methods for plating from a copper sulphate bath directly on to steel ". 

In this work, the waste brewery yeast and Aspergillus niger were used for the adsorption of lead, copper and cadmium, and their cyanide complexes. Biosorption equilibrium was studied in a batch reactor with respect to pH, initial concentration of heavy metal and metal-cyanide complex. Biosorption equilibrium over the temperature range of 288K - 308K was investigated and the biosorption heat was evaluated. 

Thus, co-deposition of silver and copper can take place only when the silver concentration in the electrolyte falls to a very low level. This clearly indicates that the electrolytic process can, instead, be used for separating copper from silver. When both silver and copper ions are present, the initial deposition will mainly be of silver and the deposition of copper will take place only when the concentration of silver becomes very low. Another example worth considering here is the co-deposition of copper and zinc. Under normal conditions, the co-deposition of copper and zinc from an electrolyte containing copper and zinc sulfates is not feasible because of the large difference in the electrode potentials. If, however, an excess of alkali cyanides is added to the solution, both the metals form complex cyanides the cuprocyanide complex is much more stable than the zinc cyanide complex and thus the concentration of the free copper ions available for deposition is considerably reduced. As a result of this, the deposition potentials for copper and zinc become very close and their co-deposition can take place to form alloys. 

Organic pollutants Pesticides Metals Antimony Arsenic Asbestos Beryllium Cadmium Chromium Copper Cyanide Lead Mercury Nickel Selenium Silver Thallium Zinc... 

Metals and inorganics Antimony Arsenic Beryllium Cadmium Chromium Copper Cyanide Lead Nickel Selenium Zinc Organics Toluene Chloroform... 

A copper cyanide strike may still be necessary for steel, zinc, or tin-lead base metals Requires good preplate cleaning Noncyanide process eliminates carbonate buildup in tanks... 

Skin Contact Wash skin at once to remove cyanide while removing all contaminated clothing including shoes do not delay Skin absorption can take place from cyanide dust, solutions, or hydrogen cyanide vapor. Absorption is slower than with inhalation, often measured in minutes rather than seconds (AC or HCN is absorbed much faster than metal cyanides from solutions such as sodium, potassium or copper cyanide solutions). After going though decontamination on the victim(s), watch him or her for at least one to two hours, if possible, since absorbed cyanide can continue to work into the blood stream. As a final note, wash clothing before reuse, and destroy contaminated shoes. 

DSA-02 oxide-coated Ti anode (DSA = Dimensionally Stable Anode) is placed, thus creating a large cathode volume. The effluent solution flows perpendicularly through the electrodes with a typical flow rate of 0.5 dm3 s-1. The flowthrough metal electrodes have an active area approximately 15 times their geometric area. The cell allows air sparging to increase the mass-transfer. The current efficiency is about 40% when the inlet concentration of the metal ions is 150 to 1500 ppm and the concentration at the out-let is about 50 ppm. The cell is currently used for the treatment of recirculated wash-waters from acid copper, copper cyanide, zinc cyanide, zinc chloride, cadmium sulphate, cadmium cyanide and precious metal plating and washwaters from electroless copper deposition. Since the foam metal electrodes are relatively expensive the electrodes... 

The preparation and reactions of metal cluster ions containing three or more different elements is an area with a paucity of results. The metal cyanides of Zn, Cd (258), Cu, and Ag (259) have been subjected to a LA-FT-ICR study and the Cu and Ag complex ions reacted with various reagents (2,256). The [M (CN) ]+ and [M (CN) +11 ions of copper, where n = 1-5, were calculated to be linear using the density functional method. The silver ions were assumed to have similar structures. The anions [M (CN) +1 of both copper and silver were unreactive to a variety of donor molecules but the cations M (CN) H + reacted with various donor molecules. In each case, where reactions took place, the maximum number of ligands added to the cation was three and this only occurred for the reactions of ammonia with [Cu2(CN)]+, [Cu3(CN)2]+, [Ag3(CN)2]+, and [ Ag4(CN)3]+. Most of the ions reacted sequentially with two molecules of the donor with the order of reactivity being Cu > Ag and NH3 > H2S > CO. 

Intimate mixtures of chlorates, bromates or iodates of barium, cadmium, calcium, magnesium, potassium, sodium or zinc, with finely divided aluminium, arsenic, copper carbon, phosphorus, sulfur hydrides of alkali- and alkaline earth-metals sulfides of antimony, arsenic, copper or tin metal cyanides, thiocyanates or impure manganese dioxide may react violently or explosively, either spontaneously (especially in presence of moisture) or on initiation by heat, friction, impact, sparks or addition of sulfuric acid [1], Mixtures of sodium or potassium chlorate with sulfur or phosphorus are rated as being exceptionally dangerous on frictional initiation. 

In a mixed copper-zinc solution of complex cyanide, however, the Cu ion concentration can be reduced to the order of lO mol/L and the concentration ratio (zinc ion)/(copper ion) will be made very large. A detailed calculation for this case is given by Faust in the 1974 edition of Modem Electroplating (1). It is shown there, and in detail below, that the copper cyanide complex is Cu(CN)3 , for which the dissociation value is known. The dissociation constant for the zinc cyanide complex, Zn(CN)4 , is also well known. Using those values that determine the fraction concentration of the free metal ion in solution and assuming an initial specific molar concentration, it is shown below that their respective reversible electrode potentials [see also Eq. (11.1)] can be brought together. 

Copper(l) cyanide is used in copper plating of nickel, chromium, zinc alloys, steel, and other metals or alloys. Such copper plating imparts brightness, smoothness, hardness, and strength. The cyanide solution employed for copper electroplating consists of copper cyanide and sodium cyanide. Other apph-cations of this compound are as an insecticide, a catalyst in polmerization, and as an antifouling agent in marine paints. 

According to the technology developer, geochemical fixation can treat dissolved hexavalent chromium and other metals in groundwater at concentrations ranging from the detection limit to several hundred parts per milhon. The developer asserts that geochemical attenuation can treat most of the common heavy metals, trace elements, and namral radionuclides that occur in groundwater, such as metal-cyanide complexes, arsenic, cadmium, chromium, copper, lead, selenium, uranium, and radium. 

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