Abstract: A method includes: (1) adding a food-grade manganese sulfate solution and a complexing agent solution into a sodium ferrocyanide solution for a precipitation reaction to generate Prussian white crystal nucleus; (2) replacing the food-grade manganese sulfate solution with an industrial-grade manganese sulfate solution, and keeping other conditions unchanged, so that the Prussian white crystal nucleus grow continuously to obtain a slurry; and (3) successively subjecting the slurry to an aging reaction, solid-liquid separation, washing and drying to obtain a Prussian white product with a specific particle size. The food-grade manganese sulfate solution, and the sodium ferrocyanide solution are subjected to the precipitation reaction, and then the industrial-grade manganese sulfate solution are added to continue a precipitation reaction. The particle size of the Prussian white is regulated by controlling an adding time of the two manganese sulfate solutions.

Abstract: Stable solutions comprising high concentrations of charged coordination complexes, including iron hexacyanides are described, as are methods of preparing and using same in chemical energy storage systems, including flow battery systems. The use of these compositions allows energy storage densities at levels unavailable by other iron hexacyanide systems.

Abstract: A system and method for efficiently purifying a starting material for a TMCC final product as well as a system and method for efficiently producing high quality TMCC material using the purified starting material.

Abstract: A method is provided for synthesizing sodium iron(II)-hexacyanoferrate(II). A Fe(CN)6 material is mixed with the first solution and either an anti-oxidant or a reducing agent. The Fe(CN)6 material may be either ferrocyanide ([Fe(CN)6]4?) or ferricyanide ([Fe(CN)6]3?). As a result, sodium iron(II)-hexacyanoferrate(II) (Na1+XFe[Fe(CN)6]Z.MH2O is formed, where X is less than or equal to 1, and where M is in a range between 0 and 7. In one aspect, the first solution including includes A ions, such as alkali metal ions, alkaline earth metal ions, or combinations thereof, resulting in the formation of Na1+XAYFe[Fe(CN)6]Z.MH2O, where Y is less than or equal to 1. Also provided are a Na1+XFe[Fe(CN)6]Z.MH2O battery and Na1+XFe[Fe(CN)6]Z.MH2O battery electrode.

Abstract: A method of manufacturing an active material having a sufficient discharge capacity at a high discharge current density, an active material obtained thereby, an electrode using the same, and a lithium-ion secondary battery equipped therewith are provided. The method of manufacturing an active material comprises a step of polymerizing a mixture containing an Fe ion, an Li ion, a PO4 ion, a hydroxy acid, and a polyol, the mixture containing the polyol by a molar ratio 1.3 to 16 times that of the hydroxy acid, so as to yield a polymer; and a step of heating the polymer, so as to yield an active material containing an active material particle and carbon. The active material particle is mainly composed of LiFePO4.

Abstract: An agent for imaging of a biological system or delivering drugs to a biological system including one or more nanoparticles formed of at least one gadolinium coordination polymer.

Abstract: Provided is a method of remediating cyanide-contaminated soil. The method is provided to remediate soil contaminated with cyanide and treat the cyanide, which includes collecting the soil contaminated with first cyanide in a solid state and second cyanide in a gaseous or dissolved state, dissociating cyanide by mixing the soil with an alkali washing solution, dissolving the first cyanide in a solid state in the washing solution, and transferring the second cyanide in a dissolved state dissociated from the soil to the washing solution, dissociating the soil from the washing solution, precipitating the first cyanide in a solid state by acidifying the washing solution containing the cyanide, and performing post-treatment on the first cyanide after the first cyanide precipitated in a solid state is dissociated from the washing solution.

Abstract: A method for producing metal complex nanoparticles, the method having: providing an aqueous solution containing a metal cyano complex anion having a metal atom MA as a central metal, with an aqueous solution containing zinc cation, the pH of the aqueous solution containing zinc cation being adjusted; and mixing the solutions and thereby producing metal complex nanoparticles composed of the metal atom MA and zinc under controlling the properties of the obtained metal complex nanoparticles.

Abstract: Disclosed is a method for producing ultrafine particles of a Prussian blue-type metal complex wherein (A) an aqueous solution containing an anionic metal cyano complex having a metal atom M1 as the central metal is mixed with an aqueous solution containing metal cations of a metal atom M2 for precipitating a crystal of a Prussian blue-type metal complex having the metal atom M1 and the metal atom M2; then (B) a solution obtained by dissolving a ligand L in a solvent is mixed with the crystal of the Prussian blue-type metal complex for forming a dispersion liquid of ultrafine particles of the Prussian blue-type metal complex; and the (C) the Prussian blue-type metal complex is separated from the dispersion liquid as nanometer-sized ultrafine particles.

Abstract: A chemical process that recovers the vanadium contained in inorganic acid solutions, precipitating it as a solid compound of vanadium and alkali metal or monovalent cation ferrocyanide, is disclosed. Separation is carried out electrochemically, depositing the compound onto a metal immersed in the acid solution that contains vanadium as well as other dissolved metals, to which a ferrocyanide salt of an alkali metal or a monovalent cation has been previously added. If the inorganic acid present in solution is different than nitric acid, the vanadium can also be separated by direct addition of a ferrocyanide salt of an alkali metal or a monovalent cation to the acid solution containing vanadium. The method described allows recovery of vanadium without modifying the initial composition of the solution, except for the concentration of the vanadium dissolved.

Abstract: A method is described for the manufacture of hydrotalcites by using at least one compound of a bivalent metal (Component A) and at least one compound of a trivalent metal (Component B), wherein at least one of these components is not used in the form of a solution, characterized in that a) at least one of the Components A and/or B which is not used in the form of a solution, shortly before or during mixing of the components, and/or b) the mixture containing the Components A and B is subjected to intensive grinding until an average particle size (D50) in the range of approx. 0.1 to 5 ?m is obtained, and optionally, after aging treatment or hydrothermal treatment, the resulting hydrotalcite product is separated, dried, and optionally calcinated.

Abstract: An improved method for synthesizing a double metal cyanide (DMC) catalyst combines and sonicates aqueous and non-aqueous solutions of a first metal salt, such as Zn(OAc)2, of a second metal salt, such as CoCl2, and of an alkali metal cyanide, such as NaCN, to synthesize the DMC catalyst, Zn3[Co(CN)6]2. An improved method of producing a polyether polyol uses the DMC catalyst to produce the polyol.

Abstract: An improved method for synthesizing a double metal cyanide (DMC) catalyst includes combining a non-aqueous solution of a first metal salt, such as ZnBr2, with a non-aqueous solution of a second metal salt, such as CoBr2, and with a non-aqueous solution of an alkali metal cyanide, such as NaCN, in a single step to synthesize the DMC catalyst, Zn3[Co(CN)6]2.

Abstract: The present invention provides a crystalline, hydroxide containing double metal cyanide (DMC) catalyst of the formulae (I) or (II), M1x[M2(CN)6]yOH.L??(I) M1x[M2(CN)6]y.zM1(OH)q.L (II) wherein M1 represents a metal selected from Zn+2, Fe+2, Ni+2, Mn+2, Co+2, Sn+2, Pb+2, Fe+3, Mo+4, Mo+6, Al+3, V+4, V+5, Sr+2, W+4, W+6, Cu+2 and Cr+3, M+2 represents a metal selected from Fe+2, Fe+3, Co+2, Co+3, Cr+2, Cr+3, Mn+2, Mn+3, Ir+3, Ni+2, Rh+3, Ru+2, V+4 and V+5, L represents an organic ligand and x, y and q are chosen to maintain electroneutrality. Further provided are processes for the production of the inventive DMC catalysts. The crystalline, hydroxide containing DMC catalysts of the present invention may find use in the preparation of polyols, such as polyether polyols.

Abstract: Catalyst suspensions for the ring-opening polymerization of alkylene oxides comprise a) at least one multimetal cyanide compound having a crystalline structure and a content of platelet-shaped particles of at least 30% by weight, based on the multimetal cyanide compound, and b) at least one organic complexing agent c) water and/or d) at least one polyether and/or e) at least one surface-active substance, with the proviso that at least component a) and at least two of the components b) to e) have to be present.

Abstract: The invention relates to double-metal cyanide catalysts for preparing polyols by the polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms, wherein the DMC catalysts are composed of: a) at least one double-metal cyanide compound; b) at least one organic complexing ligand; and, optionally, c) at least one functionalized polymer, wherein the organic complexing ligand is a mixture of a C3-C7 aliphatic alcohol and from about 2 to about 98 mole %, based on the total amount of organic complexing ligand, of a cyclic, aliphatic, cycloaliphatic or aromatic ketone. The DMC catalysts of the present invention have increased activity compared to known catalysts. Additionally, the DMC catalysts of the present invention can be used to prepare polyols with reduced high molecular weight components.

Abstract: A process for preparing multimetal cyanide compounds by reacting a metal salt with a cyanometalate compound comprises the steps

Abstract: The invention relates to double-metal cyanide catalysts for preparing polyols by the polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms, wherein the DMC catalysts are composed of: a) at least one double-metal cyanide compound; b) at least one organic complexing ligand; and, optionally, c) at least one functionalized polymer, wherein the organic complexing ligand is a mixture of a C3-C7 aliphatic alcohol and from about 2 to about 98 mole %, based on the total amount of organic complexing ligand, of a cyclic, aliphatic, cycloaliphatic or aromatic ketone. The DMC catalysts of the present invention have increased activity compared to known catalysts. Additionally, the DMC catalysts of the present invention can be used to prepare polyols with reduced high molecular weight components.

Abstract: In multimetal cyanide complexes, more than 30% by weight of the primary particles have a platelet-like habit, i.e. the length and width of the primary particles is at least three times the thickness of the particles.

Abstract: An improved process for the removal of cyanide ion from aqueous dispersions (e.g., aqueous spent cadmium plating solutions or plating rinse water solutions) is provided wherein a source of Fe+2 ion is reacted with a cyanide ion-containing aqueous dispersion at low pH to form a relatively insoluble reaction product complex, whereupon the reaction product is removed by filtration or the like. In preferred practice, the pH of a waste water is adjusted to a level of up to about 2, followed by the addition of ferrous ammonium sulfate.

Abstract: There is provided a flash activated hydrotalcite which, when extruded to sizes of about 1/16 inch or more, has a crush load strength of at least about 7 pounds. The process for making this extrudate includes: (a) providing a hydrotalcite compound; (b) heating said compound for less than two seconds to one or more temperatures above about 482.degree. C. (900.degree. F.); (c) cooling said heated compound; (d) collecting said cooled compound; (e) forming said compound into an extrudate; and (f) reactivating said extrudate by heating to one or more temperatures above about 400.degree. C. (752.degree. F.) for about 20 minutes or more. Further strength improvements are achieved by exposing these extrudates to steam for at least about 8 hours prior to step (f).

Abstract: A method for producing aromatic amines such as N-phenyl-p-phenylenediamine is disclosed wherein an amine substituted aromatic such as aniline is oxidized with oxygen or hydrogen peroxide in the presence of trisodium pentacyano ferrate(II) complexes containing various water soluble ligands, such as ammonia, mono alkyl amine, dialkyl amines, and trialkyl amines. The complex is subsequently catalytically reduced by hydrogenation using certain heterogeneous metal catalysts to yield the desired aromatic amine.

Abstract: A method for treating cyanide contaminated water is disclosed. This method generally involves passing the contaminated water through a bed containing elemental iron, to form a precipitate by a reaction between the iron and any of various cyanide species which exist in the water. The method can be applied either above ground or in situ in the subsurface environment.

Abstract: There is provided a method for making a monovalent inorganic anion-intercalated hydrotalcite-like material by first reacting a magnesium-containing powder and a transition alumina powder in a carboxylic acid-free, aqueous suspension to form a meixnerite intermediate. This intermediate is then contacted with a monovalent inorganic anion, in its acid or soluble salt form, to make a hydrotalcite-like material. The latter is then separated from the suspension. Representative materials include a bromide-, chloride-, nitrate- or vanadate-intercalated, hydrotalcite-like material.

Abstract: There is provided a method for making a polyvalent inorganic anion-intercalated hydrotalcite-like material by first reacting a magnesium-containing powder and a transition alumina powder in a carboxylic acid-free, aqueous suspension to form a meixnerite intermediate. This intermediate is then contacted with a polyvalent inorganic anion, in its acid, acid salt or ammonium salt form, to make a hydrotalcite-like material. The latter is then separated from the suspension. Representative materials include a borate- metatungstate- and paramolybdate-intercalated hydrotalcite-like material.

Abstract: There is provided an improved method for making synthetic hydrotalcite by first reacting powdered magnesium oxide with a high surface area, transition alumina in a solution or suspension to form a meixnerite-like intermediate. This intermediate is then contacted with an anion source such as an acid, and most preferably carbon dioxide, to form the layered double hydroxide which is separated from the suspension by filtering, centrifugation, vacuum dehydration or other known means. On a preferred basis, the transition alumina combined with activated magnesia consists essentially of an rehydratable alumina powder having a surface area of 100 m.sup.2 /g or greater. To make related double hydroxide compounds, still other reactants such as bromides, chlorides, boric acids, or salts thereof, may be substituted for the carbon dioxide gas fed into this suspension.

Abstract: There is provided a method for making a divalent inorganic anion-intercalated hydrotalcite-like material by first reacting a magnesium-containing powder and a transition alumina powder in a carboxylic acid-free aqueous suspension to form a meixnerite intermediate. This intermediate is then contacted with a divalent inorganic anion, in its acid, acid salt or ammonium salt form, to make a hydrotalcite-like material. The latter is then separated from the suspension. Representative materials include a sulfate- and metavanadate-intercalated hydrotalcite-like material.

Abstract: There is provided a method for making monovalent organic anion-intercalated hydrotalcite-like materials by first reacting a magnesium-containing powder and a transition alumina powder in a carboxylic acid-free, aqueous suspension to form a meixnerite intermediate. This intermediate is then contacted with a monovalent organic anion to form a hydrotalcite-like material. The latter is then separated from the suspension. Representative materials include a stearate-, acetate- or benzoate-intercalated hydrotalcite-like material.

Abstract: There is provided an improved method for making synthetic hydrotalcite by first reacting a divalent metal compound with a trivalent metal oxide powder in a carboxylic acid-free, aqueous solution or suspension to form an intermediate. This intermediate is then contacted with an anion source such as carbon dioxide; a carbonate-containing compound; an acid or an ammonium salt to form a layered double hydroxide having the formula:A.sub.1-x B.sub.x (OH).sub.2 C.sub.z.mH.sub.2 O, where A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to polyvalent anion, and x, z and m satisfy the following conditions: 0.09<x<0.67; z=x/n, where n=the charge on the anion; and 2>m>0.5. Said layered double hydroxide is typically separated from the suspension by filtering, centrifugation, vacuum dehydration or other known means.

Abstract: A method and apparatus for the removal of total cyanide from aqueous solution. The method includes the steps of placing the aqueous solution into a reaction tank, adding lime, ferrous sulfate, and acid to the solution in the reaction tank and agitating the resultant mixture for a reaction time of about one hour. The agitated mixture is transferred from the reaction tank to a clarifier tank and polyelectrolyte solution is added to induce iron-cyanide complex precipitate coagulation. The apparatus includes a reaction tank to hold the aqueous solution and a lime slurry tank, ferrous sulfate tank and acid tank in flow communication with the reaction tank. A pH control assembly controls the flow of acid from the acid tank into the reaction tank and a reaction tank agitation assembly extends into the interior of the reaction tank. The clarifier feed conduit extends between the reaction tank and a clarifier tank.

Abstract: Impurity streams generated during the metallurgy of copper are hydrometallurgically processed at ambient pressure for recovery of primary values in an energy-efficient manner and with the capture and conversion of metallic impurities to states that are acceptable for disposal into the environment. Hallmark features of the various embodiments of this invention include the water leach of flue dust, a controlled acid leach stage in which metal species are solubilized, the extraction of copper as a sulfide, and the ability to operate the various process stages at essentially ambient pressure.

Abstract: There is provided a method for making a divalent or polyvalent organic anion-intercalated hydrotalcite-like materials by first reacting a magnesium-containing powder and a transition alumina powder in an aqueous suspension to form a meixnerite intermediate. This intermediate is then contacted with a dicarboxylate or polycarboxylate anion to form a hydrotalcite-like material. The latter is then separated from the suspension. Representative materials include an oxalate-, succinate- or terephthalate-intercalated hydrotalcite-like material.

Abstract: A process for removing cyanide anions from waste waters using halogen-free ferric salts is disclosed. The process is particularly effective when treatment of cyanide waste waters is done by adding ferric sulfate while adjusting pH of the waste waters with a halogen-free acid, such as sulfuric acid, to a pH ranging from about 3.0 to 5.0.The ferric ferricyanides formed are agglomerated and flocculated using synthetic polymers along with whatever other dispersed or suspended solids may be present in the waste waters, and this dense sludge is separated in a clarifier. Cyanide removal is at least 80%, relative to initial cyanide concentrations, and preferably 90% removal or higher.Cyanide wastes from coke oven off gas scrubbing waters are particularly waste waters amenable to this treatment.

Abstract: An eta phase composition in powder form, prepared in the absence of sulfur or sulfur bearing compounds, having a surface area greater than about 2m.sup.2 /g and consisting of X.sub.6 Y.sub.6 Z.sub.a wherein X is at least one element selected from the group consisting of Mo and W, Y is at least one element selected from the group consisting of Fe, Co, Ni, Mo and W, Z is at least one element selected from the group consisting of C, N and combinations thereof such that when Z is N, a is greater than or equal to 1 but less than or equal to 2 and when Z is C, a is greater than 1 but less than or equal to 2 except when Z is C and Y is Fe, then a is greater than or equal to 1 but less than or equal to 2. The eta phase may be a carbide, nitride or carbonitride. A method for producing the eta-phase composition includes providing a precursor compound including at least two eta-phase forming metals, and a ligand containing carbon, nitrogen or combinations thereof.

Abstract: A process for the removal of cyanide and other impurities from an aqueous solution is disclosed. The process comprises adding copper ion and ferrous ion as reagents to the solution at a pH of about 4 to 8 with a ratio of copper to cyanide in the range of 3:1 to 10:1 by weight and with a ratio of iron to copper of at least 0.3:1 by weight.

Abstract: A method of producing an algae growth-repellent underwater coating and the resultant product is to be such that it can be operated and performed without causing environmental pollution.For that purpose, there is added to an underwater paint or the like, a zinc-bearing additive comprising (CN).sub.6 -complex salts of hydrocyanic acid, in particular hexacyano iron(II) acid or hexacyano iron(III) acid. Zinc ferrocyanide and/or zinc ferricyanide is/are added to a colorless underwater paint, as a sole or additional pigment, in particular mixed with potassium ferrocyanide or ferricyanide or yellow soda or yellow calcium.

Abstract: A process for removal of iron cyanide complex or complexes from a solution is described, the process being characterized by contact of the solution containing the complex or complexes with ammonium polysulfide or sodium polysulfide, or a mixture thereof, at a temperature of from about 110.degree. C. to about 180.degree. C.

Abstract: A process for treatment of cyanide-containing aqueous effluents in which ferrocyanide present is precipitated with a metal other than copper, preferably zinc either prior to or simultaneously with the treatment of the effluent with sulfur dioxide and air in the presence of soluble copper.

Abstract: A method of removing complexed zinc-cyanide from wastewater involving a multiple stage process including, in a first step, control of ferrous ions to a critical minimum concentration of 250 to 400 ppm, together with pH control in the first and also a second step, together with recycling of a portion of sludge precipitated in the process. Improved sludge stability is achieved by aeration to oxidize precipitated ferrous hydroxide to ferric hydroxide, immediately before settling the sludge in a thickener.

Abstract: A method of removing complexed zinc-cyanide from wastewater involving a multiple stage process including, in a first step, control of ferrous ions to a critical minimum concentration of 250 to 400 ppm, together with pH control in the first and also a second step, together with recycling of a portion of sludge precipitated in the process.

Abstract: The invention provides an improvement in the disposal of a waste water coining iron-cyanide complexes including ferricyanides by the reduction of the ferricyanide ions into ferrocyanide in the presence of a zinc salt to precipitate the ferrocyanide ions in the form of zinc ferrocyanide. The improvement comprises the use of a sulfite, e.g. sodium sulfite, and a thiosulfate, e.g. sodium thiosulfate, in combination as the reducing agent whereby the reduction of the ferricyanide ions is complete within a relatively short time without being affected by the atmospheric oxygen or other factors.

Abstract: The subject invention relates to a process for preparing ferriferrocyanide pigments. The process comprises(a) forming an aqueous reaction mixture comprising(i) a ferrous salt,(ii) a compound selected from the group consisting of sulfuric acid, hydrochloric acid, an inorganic potassium salt, and mixtures thereof, and(iii) an alkali metal ferrocyanide such that the molar ratio of (i) to (ii) to (iii) is about 1:1 to 0.9:1.5 to 1:1;(b) oxidizing the acidic solution by aeration;(c) heating the aerated solution to from 10.degree. C. to 90.degree. C.; and(d) recovering the pigment.

Abstract: The subject invention relates to a process for preparing ferriferrocyanide pigments. The process comprises(1) forming a reaction mixture containing a ferrous salt and an alkali metal ferrocyanide;(2) adding an alkaline compound to said reaction mixture in an amount sufficient to raise the pH to at least 9;(3) oxidizing the basic solution by aeration;(4) heating the solution to a temperature of from 10.degree. C. to 90.degree. C. and(5) recovering the pigment.The advantage of the process is that no significant amount of Berlin White intermediate is formed. Consequently, it is unnecessary to use sulfuric acid to dissolve the Berlin White before oxidation. Moreover, oxidation is achieved by aeration. This is cost effective and reduces the stress to the environment. The resulting pigments are useful in coloring printing ink and carbon paper.

Abstract: Iron (II) hexacyanocobaltate and ruthenium (III) hexacyanocobaltate have been found to be useful in the catalytic hydrogenation of organic materials.

Abstract: Iron blue pigment (DIN 55 906) is produced by white paste precipitation and subsequent oxidation of the white paste. Alakli or alkali metal ions i.e. sodium and potassium ions, cyanide or complex iron cyanide ions and iron ions are used as raw materials. The iron blue pigment according to the invention is characterized by a potassium content of 0.5-4.5% by weight, preferably 0.5-2.0% by weight, a sodium content of 0.2-1.0% by weight, an ammonium content of 2.0-4.5% by weight, preferably 3.0-4.5% by weight, a coloring power in accordance with DIN 53 204 and DIN 53 234 of 5-15% above the Vossen Blue 705 Standard and the following color intervals (determined in accordance with DIN 53 204 and DIN 53 234 in conjunction with DIN 6174, in relation to Vossen Blue 705 as standard):.DELTA.L: -0.7 to -1.5.DELTA.a: -0.5 to 1.5.DELTA.b: -0.6 to -2.3.DELTA.C: +0.5 to 2.

Abstract: A method of removing ferrocyanide ions from the rinse water of an alkaline cyanide metal plating process which comprises adding a sufficient amount of manganous ions to the rinse water containing ferrocyanide ions to form a water insoluble precipitate of manganous ferrocyanide [Mn.sub.2 Fe (CN).sub.6 ] which can be readily separated from the rinse water.

Abstract: Synthesis of ammonia employing at least one salt selected from alkali metal-, an alkaline earth metal-, iron- and cobalt hexacyanocobaltate and hexacyanoruthenate on a suitable support and then heating the composition to provide it with suitable activity.

Abstract: Spent aqueous liquor containing cyanide, as from ore treatment, is passed through a bed of suitable anion-exchange resin to segregate the cyanide, which is subsequently recovered in regeneration of the resin by weak alkaline solution. Both the eluted cyanide and the alkaline regenerant are recycled, if desired, for further ore treatment. A most important benefit of such procedure is nearly complete elimination of cyanide as a component of the treatment effluent. Free cyanide may be separated from complexed cyanides when present by using weak alkaline regenerant to elute the free cyanide from the resin and stronger alkaline regenerant to elute the complexed cyanides.

Abstract: Inert gas-permeable granular support materials impregnated with alkali ferrates wherein the ferrates are iron compounds having an oxidation state of +4, +5, or +6 are disclosed. When they are used as a granular filter material in combination with a tobacco product, hydrogen cyanide can be significantly reduced in the smoke obtained from the tobacco product. Activated carbon or alumina impregnated with sodium permanganate and a basic sodium compound may also be combined with the granular filter material.

Abstract: A method is provided for the treatment of a waste water stream characterized by having toxic and corrosive properties due to the presence of a cyanides formates and a halide of a metal or ammonia comprising adding a ferrous ion to said waste water to convert the cyanides to iron cyanides, adding a base to said waste water until the pH of said waste water is adjusted to the range from about 9 to 11 to precipitate a sludge containing said iron cyanides, feeding said waste water to a biological reactor to convert said formates to carbon dioxide and a biological residue and recovering an environmentally upgraded waste water stream from said biological reactor.