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1. (WO2016191833) METHOD FOR PROCESSING INDUSTRIAL WASTE CONTAINING IRON
Nota: Texto obtenido mediante procedimiento automático de reconocimiento óptico de caracteres.
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CLAIMS

1. A method of processing industrial waste containing iron and comprising steps of leaching with oxalic acid at continuous stirring, treatment with hydroxide of an alkali metal at a raised temperature and continuous addition of aqueous hydrogen peroxide solution, characterized in that it comprises the following steps:

(a) mixing of an iron containing industrial waste in the form of a pulp with a 25-40% of aqueous sodium hydroxide solution and heating to 35-80°C with a stirring;

(b) continuous addition at the same temperature of an oxalic acid solution saturated at 20 to 60 °C together with 0.5 - 10% of aqueous hydrogen peroxide solution until an equivalent molar proportion of Na:Fe:C204 = 3:1:3 is achieved;

(c) addition of an excess of 5-10% of the oxalic acid with regard to the already added quantity of this acid and heating at 25-80°C for 1 hour;

(d) filtering of the reaction mixture with separation of the solid phase and precipitation of the filtrate with a 5-15% aqueous sodium hydroxide solution at 60-70°C;

(e) washing of the precipitate from step (d) with a deionized water and drying at 115-160°C;

(f) treatment of the solid phase separated after step (c) with 15-30% of sulphuric acid.

2. A method of processing industrial waste containing iron according to claim 1, characterized in that the solid phase separated after step (c) is treated with 11-15% of aqueous sodium hydroxide solution.