Abstract: A bath for electroplating palladium employs a combination of an aliphatic amine compound and an alicyclic amine compound as metal ion complexing agents.

Abstract: A solution for simultaneously stripping gold and palladium-containing deposits from substrates carrying them is provided, which is capable of efficient operation under practical and desirable conditions, particularly for recovering the precious metal electroplate and flash coatings from electronic components. The solution contains a thallium compound, in addition to a nitrobenzoate derivative, a soluble cyanide, and certain optional ingredients.

Abstract: A bath for electrodepositing gold utilizes, as the essential ingredients of its electrolyte, salts providing the tartrate radical and the carbonate radical. The bath will have a pH value ranging from approximately neutral to highly alkaline, and adjustments to lower the pH will most advantageously be made utilizing tartaric acid. The bath operates with relatively low gold concentrations, and is capable of producing highly pure deposits and highly desirable alloy deposits; it is especially well suited for semi-conductor industry applications.

Abstract: An all-purpose gold cyanide electroplating bath utilizes a cobalt, nickel, or indium hardener as a chelate with the acid form of a methyl vinyl ether/maleic anhydride interpolymer. The bath is capable of producing high levels of hardness in deposits that are substantially pure gold; it is efficient, very stable, resistent to contamination, and it is well-suited for utility at a wide range of current densities.

Abstract: An aqueous bath for the electroplating of gold is particularly adapted for plating a gold strike on stainless steel and includes about 2 to 16.5 grams per liter of auric(III) gold in a cyanide complex. Potassium nitrate is employed as an electrolyte and ethylenediamine hydrochloride is added as a complexer. Nickel, cobalt, copper, tin, or indium ions may be present as an alloying ingredient for the gold and pH of the bath is not more than 4.0, preferably not more than 1.5. In the method of preparing the bath, an aqueous solution of potassium gold chloride KAu(Cl).sub.4 and potassium nitrate is prepared. Potassium cyanide is added to the solution and reacts with the potassium gold chloride to form a gold cyanide complex. Ethylenediamine hydrochloride is then added to the solution. The ethylenediamine hydrochloride may include nickel chloride or other salts to provide the alloying metal additives for the gold and hydrochloric acid may be added to adjust the pH.

Abstract: A bath for electroplating substantially pure silver deposits includes 2-240 grams per liter of alkali metal silver cyanide, a water-soluble electrolyte and a water-soluble selenium compound containing selenium in the -2 oxidation state. The bath has a pH of 8-10 and a free cyanide content of less than 1.5 grams per liter. The bath is maintained at a temperature of 18.degree.-24.degree. Centigrade and may be operated to provide current densities of 0.1-75 amperes per square decimeter.

Abstract: Precious metals such as gold and silver are recovered from aqueous cyanide solutions thereof by a stepwise process. The pH of the solution is, if necessary, initially adjusted to about 13 and thereafter is adjusted and maintained at 10 or above throughout the process. A "starter" carbonyl compound (e.g., formaldehyde or dextrose) which reacts with free cyanide ions is dissolved in the solution. Following this, an "accelerator" (e.g., hydrogen peroxide or a persulfate) is added and the solution is heated to aid in conversion of free cyanide ions to other chemical species. Finally, a "clarifier" (e.g., hydrazine or a hydrosulfite) is added and the elevated temperature is maintained for at least a brief period after the addition. The solution is then cooled and the elemental precious metal particles formed are allowed to settle and are separated from the supernatant solution.

Abstract: A process for making high purity alkali produced is sulfite substantially free from chloride ions includes the step of admixing gold chloride solution with magnesium oxide at an alkaline pH to form magnesium aurate which is recoverable as a coating upon the magnesium oxide precipitate. The magnesium aurate is thereafter admixed with a solution of alkali metal sulfite at an alkaline pH to produce alkali metal gold sulfite and a precipitate of magnexium oxide.When the alkali metal gold sulfite being produces ia a potassium gold sulfite, the process desirably includes the step of admixing the potassium gold sulfite with a sulfamic acid compound to provide stability. The magnesium aurate precipitate is desirably rinsed to remove chloride ion contamination.