RU99120294A - METHOD AND DEVICE FOR THE PREPARATION OF PRODUCTS FROM METAL ALLOYS IN THE ABSENCE OF NITRIC ACID AND FOR THE REGENERATION OF FINISHED SOLUTIONS PRODUCED AFTER ETCHING - Google Patents

Claims (14)

1. The method of etching products from a metal alloy containing iron, and products from titanium and its alloys, including the stage of immersion of the product to be etched in an aqueous solution of sulfuric acid, hydrofluoric acid and, optionally, phosphoric and hydrochloric acid, in the absence of nitric acid, moreover, the oxidant in the pickling solution is ferric ion or ions of titanium (III) and titanium (IV), and the stage of regeneration of spent solutions, characterized in that the regeneration of spent pickling solutions contains um following steps: supplying an etching solution in the form of a cathode and an anode in the form of an electrolyte in an electrolytic cell optionally of the membrane type, for
a) separation of Fe ²⁺ or Ti ^{2+ ions} to be isolated from Fe ³⁺ or Ti ³⁺ and Ti ⁴⁺ ions to be reduced, performed by reducing the Fe ³⁺ ions to Fe ²⁺ or Ti ³⁺ ions on the cathode and Ti ⁴⁺ to Ti ²⁺ , and by oxidation at the anode of ions Fe ²⁺ or Ti ²⁺ to ions Fe ³⁺ or to ions Ti ³⁺ and Ti ⁴⁺ ,
b) regeneration of F ^- as HF, in complex with Fe ³⁺ , in the cathode electrolyte by reducing the Fe ³⁺ ion to Fe ²⁺ , followed by dissociating the complex compound and releasing the F ^- ion,
processing of the cathode electrolyte coming from the electrolyzer and enriched with Fe ²⁺ or Ti ^{2+ ions} in order to ensure separation into two phases, with the first phase containing the Fe ²⁺ , Cr ³⁺ , Ni ²⁺ or Ti ²⁺ metal cations subject isolation, and the second liquid phase, devoid of the mentioned metal cations, is to be fed into the pickling bath, and the flow of anode electrolyte coming from the electrolyzer and enriched with Fe ³⁺ or Ti ³⁺ ions and Ti ⁴⁺ ions into the pickling bath. 2. The method of etching products from a metal alloy containing iron, and products from titanium and its alloys according to claim 1, characterized in that the step of processing the solution of the cathode electrolyte to separate the cations of metals Fe ²⁺ or Ti ²⁺ , Cr ³⁺ , Ni ^{The 2+} to be insulated and containing them are selected from the following types of separation treatment by crystallization (in the form of inert sulfates) through cooling, separation by ion exchange resins, separation by selective membranes. 3. The method of etching products from a metal alloy containing iron, and products from titanium and its alloys on PP. 1 or 2, characterized in that the cell membrane is an anionic membrane of a selective type, providing preferential passage of only negative ions, thereby separating also the anions of acids SO ₄ ⁼ , F ^- , Cl ^- , НРО ₄ ⁼ , which migrate in the direction of the anode electrolyte, where they then go to the pickling bath for their regeneration. 4. The method of etching metal products containing iron, and products from titanium and its alloys according to any one of paragraphs. 1-3, characterized in that the electrolyzer has an anode compartment containing an anodic electrolyte consisting of an etching solution, which is subject to regeneration in a bath, two cathode compartments, in the first of which is an etching solution for separating cations and in which reduction of Fe ³⁺ ions to Fe ²⁺ or Ti ³⁺ and Ti ⁴⁺ to Ti ²⁺ , and the second of which contains a solution of sulfuric acid and / or hydrochloric and / or phosphoric acid as the cathode electrolyte and in which the cathode p occurs reaction with the formation of hydrogen, and from which the said solution of the cathode electrolyte enters the pickling bath. 5. The method of etching metal products containing iron, and products made of titanium and its alloys according to any one of paragraphs. 1-4, characterized in that the electrolyzer has an anode compartment containing an anodic electrolyte consisting of an etching solution, which is subject to regeneration in a bath, a cathode compartment, in which an etching solution for separating cations is located as a cathode electrolyte and in which Fe ions are reduced ³⁺ to Fe ²⁺ or Ti ³⁺ and Ti ⁴⁺ to Ti ²⁺ , and at the same time a cathodic reaction occurs with the formation of hydrogen.  6. The method of etching products from a metal alloy containing iron, and products from titanium and its alloys according to any one of paragraphs. 1-5, characterized in that the working electrochemical potential at the anode of the electrolyzer is from 771 to 1229 mV SHE (standard hydrogen electrode), and the potential at the cathode is ≅771 mV SHE (standard hydrogen electrode).  7. The method of etching metal products containing iron, and products made of titanium and its alloys according to any one of paragraphs. 1-5, characterized in that the working electrochemical potential at the anode of the electrolyzer is from -502 to 1229 mV SHE (standard hydrogen electrode), and the potential at the cathode is ≅368 mV SHE (standard hydrogen electrode).  8. The method of etching metal products containing iron, and products from titanium and its alloys according to any one of paragraphs. 1-7, characterized in that the anodic reaction or, alternatively, the cathodic reaction is regulated by potentiostatic or galvanostatic.  9. The method of etching metal products containing iron, and products made of titanium and its alloys according to any one of paragraphs. 1-8, characterized in that the regeneration of the pickling solution is carried out continuously by circulating the pickling solution in the anodic electrolyte and the cathodic electrolyte of the electrolyzer or intermittently. 10. The method of etching products from a metal alloy containing iron, according to any one of paragraphs. 1-6 and 8-9, characterized in that the pickling bath is essentially an aqueous solution containing the following components:
Unbound HCl - 0 - 50 g / l,
Unbound H ₃ PO ₄ - 0 - 200 g / l,
Unbound H ₂ SO ₄ - 50 - 250 g / l,
Unbound HF - 5 - 50 g / l, and
Fe _tot (Fe ²⁺ + Fe ³⁺ ) in solution ≥50 g / l. 11. The method of etching products from titanium and its alloys according to any one of paragraphs. 1-5 and 7-9, characterized in that the anode electrolyte is an aqueous solution containing
Unbound HC1 - 0 - 50 g / l,
Unbound H ₃ PO ₄ - 0 - 200 g / l,
Unbound H ₂ SO ₄ - 50 - 250 g / l,
Unbound HF - 5 - 50 g / l, and
Fe _tot (Fe ²⁺ + Fe ³⁺ ) in solution ≥50 g / l or as an alternative
Ti _tot (Ti ²⁺ + Ti ³⁺ + Ti ⁴⁺ ) in solution ≥50 g / l.  12. Device for etching products from a metal alloy containing iron and products from titanium and its alloys and for regeneration of waste solutions produced after etching, including the following combination of components: an etching bath, an electrolyzer containing an anodic compartment, at least one cathode compartment at least one anode selected from the group comprising graphite, carbon or lead base, at least one cathode selected from the group including graphite, lead, iron, stainless steel or on the basis of nickel alloys, and a means of separation between the anodic electrolyte and the cathode electrolyte, means for controlling the electrolyzer current of galvanostatic or potentiostatic type, means for supplying the pickling solution both to the anode and cathode compartments, means for separating metal cations from the solution coming from the cathode compartment to obtain liquids devoid of ions of the mentioned metals, means for supplying the solution coming from the anode compartment into the pickling bath, and means for supplying the liquid Devoid of said metal ions in the pickling bath.  13. The device according to p. 12, characterized in that the means of separation between the solution coming from the anode compartment and the solution coming from the cathode compartment, is a selective membrane.  14. The device according to claim 12, wherein the means for separating metal cations from the cathode electrolyte solution is selected from the group consisting of a cryostat-type crystallizer, ion-exchange resins and selective membranes.