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Showing papers on "Sodium dichromate published in 1972"


Patent
20 Jul 1972
TL;DR: In this paper, the authors discuss the effects of oXidation in the kaline medium at a temperature ranging from 40* C to 100* C. For from 10 minutes to 4 hours, with a constant number of oxidisings, a 10% solution of HYDROGEN PEROXIDE, not more than three times the total weight of the entire mixture.
Abstract: 1. DYESTUFF OBTAINED BY OXIDATION OF THE COMPOUNDS OF THE FORMULA: HO-(3-(HO-)-1,4-PHENYLENE)-N=N-(4-(HO3S-)-1,3-PHENYLENE)- IN WHICH Z IS METHYL OR CARBOXY, M IS ONE OR TWO AND N IS ZERO, ONE OR TWO, THE OXIDATION BEING EFFECTED IN ALKALINE MEDIUM AT A TEMPERATURE OF FROM 40* C. TO 100* C. FOR FROM 10 MINUTES TO 4 HOURS INCLUSIVE WITH A QUANTITY OF OXIDISING AGENT, CALCUALTED AS 10% SOLUTION OF HYDROGEN PEROXIDE, NOT MORE THAN THREE TIMES THE WEIGHT OF THE COMPOUND OF THE ABOVE FORMULA, SAID OXIDISING AGENT BEING SELECTED FROM THE GROUP CONSISTING OF AIR, HYPOCHLORITE, HYDROGEN PEROXIDE, SODIUM PERMANGANATE, POTASSIUM PERMANGANATE, SODIUM DICHROMATE, POTASSIUM DICHROMATE, AND MANGANESE DIOXIDE. (SO3H)M N=N-(3-Z,5-(HO-)-PYRAZOL-4,1-YLENE)-((CL-)N-PHENYLENE)-

7 citations


Patent
08 May 1972
TL;DR: In this article, an electroplated with zinc is rapidly coated with a resistant and well adhering electroless chromium plating by immersing the articles in an aqueous bath containing A. 8 TO 15 LITERS of a solution of 250 to 350 G/L.
Abstract: Articles being electroplated with zinc are rapidly coated with a resistant and well adhering electroless chromium plating by immersing the articles in an aqueous bath containing A. 8 TO 15 LITERS OF A SOLUTION OF 250 TO 350 G./L. OF SODIUM DICHROMATE AND 200 TO 300 G./L. OF SODIUM NITRATE, SAID SOLUTION BEING ADJUSTED TO PH .3 with nitric acid, B. 3 TO 8 LITERS OF A SOLUTION OF 500 TO 700 G./L. OF 85 PERCENT FORMIC ACID AND C. .5 TO 3 LITERS OF GLACIAL ACETIC ACID AND CONCENTRATED ACETIC ACID RESPECTIVELY EACH PER 100 LITERS AND MAINTAINING THE PH value of the solution at a pH of 2.1 to 2.7.

6 citations


Journal ArticleDOI
TL;DR: In this paper, the roasting process of Egyptian chromite middling product with lime and soda was successfully performed to produce sodium chromate with a chromium recovery of 97% and an aluminum recovery of 81%.

5 citations


Patent
30 Mar 1972
TL;DR: In this paper, a method for the integrated production of chromium metal and a tanning composition which comprises acidifying an aqueous solution of sodium chromate with sufficient of an acidified solution consisting essentially of sulphuric acid to form sodium dichromate, reducing the dichromates with sulphur dioxide to form an annealing solution of basic chromic sulphate and sodium sulphate, using a part of the tanning solution diluted to a concentration of from 40 to 180 g/l chromium as feed to a chromium electrowinning operation which comprises passing
Abstract: A method for the integrated production of chromium metal and a tanning composition which comprises acidifying an aqueous solution of sodium chromate with sufficient of an aqueous solution consisting essentially of sulphuric acid to form sodium dichromate, reducing the dichromate with sulphur dioxide to form an aqueous tanning solution of basic chromic sulphate and sodium sulphate, using a part of the tanning solution diluted to a concentration of from 40 to 180 g/l chromium as feed to a chromium electrowinning operation which comprises passing a current having a density of between 30 and 300 amps/sq. ft. through an electrolyte having a pH between 1.0 and 2.8 and a temperature between 27* and 80* C and thereby producing chromium metal, an acidic anolyte and a chromium lean catholyte, maintaining the anolyte and the catholyte in separate compartments, recycling the catholyte and combining it with the tanning solution, recycling the anolyte and adding it to the alkali metal chromate as part of the said aqueous solution consisting essentially of sulphuric acid to effect part of the acidification thereof, and recovering the chromium metal and part of the tanning solution as products, the proportion of chromium metal to chromium in the total products being less than 1:3.

2 citations


Patent
15 Jun 1972
TL;DR: In this paper, a hot galvanized strip, plate or other ferrous metal workpiece is moved continuously from a cooling tower, and while at a temperature within a range of about 130° to 180° F, its zinc coating surfaces are subjected to the application of a white rust inhibiting master aqueous chemical treating solution.
Abstract: A hot galvanized strip, plate or other ferrous metal workpiece is moved continuously from a cooling tower, and while at a temperature within a range of about 130° to 180° F. its zinc coating surfaces are subjected to the application of a white rust inhibiting master aqueous chemical treating solution. The solution forms a substantially transparent protective film on the coating surfaces that is adherent thereto. The solution contains the compounds and reaction products of two solutions as mixed together, one of which is made up of sodium dichromate dissolved in and reacted with ethylene glycol and the other of which is made of potassium dichromate dissolved in and reacted with ethylene glycol.