CS276055B6

CS276055B6 - A method of removing arsenic from sulphide-alkaline solutions

Info

Publication number: CS276055B6
Application number: CS902121A
Authority: CS
Inventors: Edita Ing Csc Vircikova; Eva Ing Csc Reitznerova; Jozef Ing Javorka; Ludovit Ing Csc Bobok; Jaroslav Ing Fedor
Original assignee: Univ Tech Kosiciach
Priority date: 1990-04-27
Filing date: 1990-04-27
Publication date: 1992-03-18
Also published as: CS212190A3

Abstract

Sulfidicko-alkalický roztok sa oxiduje paroxidom vodila. pričom sa oxiduje trojmocný arzén na pátmocný a síra na síran sodný. Po okyalení roztoku zriedenou kyselinou sírovou sa do roztoku přidává oxid vápenatý, čím aa odstráni arzén vo formě nerozpustného deponovatel’ného arzeničnanu vápenatého. Dočiatenie roztoku od arzénu ea robí prídavkom síranu železnatého na deponovatelný arzeničnan železnatý. Konečný roztok síranu sodného sa odpaří, vysuší a získá sa predajný kryštalický síran sodný. Tento je možné redukovať na sulfid sodný, ktorý je možný použit’ opat na lúhovanie odpadov a obsahom arzénu.The sulphide-alkaline solution is oxidized with hydrogen peroxide, whereby trivalent arsenic is oxidized to pentavalent arsenic and sulphur to sodium sulphate. After acidification of the solution with dilute sulphuric acid, calcium oxide is added to the solution, thereby removing arsenic in the form of insoluble depositable calcium arsenate. The solution is purified from arsenic by adding ferrous sulphate to depositable ferrous arsenate. The final sodium sulphate solution is evaporated, dried and saleable crystalline sodium sulphate is obtained. This can be reduced to sodium sulphide, which can be used again for leaching waste containing arsenic.

Description

Vynález spadá do oboru chemických technologií spracovávajúclch odpadně roztoky. Rieši sa spósob spracovania toxického roztoku z hydrometalurgického spracovánia odpadov a medziproduktov s obsahom arzénu. Účelom vynálezu je s pracovat* alkalicko-sulfidický roztok na deponovatelnú zlučeninu a síran sodný. Uvedeného účelu sa dosiahne upravením roztoku oxidáciou a okyslením a následným zrázením oxldom vápenatým.The invention belongs to the field of chemical technologies for processing waste solutions. The method of processing the toxic solution from the hydrometallurgical treatment of wastes and intermediates containing arsenic is being solved. The object of the invention is to work with an alkali metal sulfide solution for a depositable compound and sodium sulfate. This object is achieved by treating the solution by oxidation and acidification and subsequent precipitation with calcium oxide.

Doteraz sa vyššie uvedené sulfídicko-alkalické roztoky po selektívnom lúhování u odpadov i a medziproduktov spracovávajú na sanitámu formu elektrolytem s obsahom síranu zinočnatého. Po odstránení síry vo forme sulfidu zinočnatého sa získá sulfid arzénu, pričom v druhom stupni sa roztok zmieša s roztokom zelenej skalice a arzén sa odstraňuje vápenným mliekom na nerozpustný arzeničnan vápenatý. Druhou meto'dou je čistenle roztokov kyselinou fosforečnou a odstranenle arzénu vo forme tloarzeničnanu a tioarzenitanu sodíka. Konečným krokem je opat odstránenie arzénu vo forme arzeničnanu vápenatého.Hitherto, the above-mentioned sulfide-alkaline solutions, after selective leaching of wastes and intermediates, have been processed to the sanitary form by an electrolyte containing zinc sulphate. After removal of the sulfur in the form of zinc sulphide, arsenic sulphide is obtained, the solution being mixed with a green rock solution in a second step and the arsenic removed with lime milk to give insoluble calcium arsenate. The second method is the purification of the solutions with phosphoric acid and the removal of arsenic in the form of sodium borate and sodium thioarsenite. The final step is again to remove arsenic in the form of calcium arsenate.

Pri rozklade priemyselných sulfidicko-alkalických roztokov kyselinami značná časť arzénu v roztoku vo forme oxitioarzeničnanu sodného, ktorý sa Sálej rozkládá.During the decomposition of industrial sulfide-alkaline solutions by acids, a considerable part of the arsenic in solution in the form of sodium oxithioartenate, which decomposes.

Pri všetkých doteraz známých metodách je možnost* tvorby sírovodíka. Pri konečnom kroku odstraňovania arzénu prídavkom vápna sa dosahujú koncentrácie arzénu v odpadnom roztoku od 0,2 do 2 g.1-1.With all known methods, the possibility of * hydrogen sulfide formation. In the final step of removing arsenic by adding lime, arsenic concentrations in the waste solution of 0.2 to 2 g.1-1 are achieved.

Vyššie uvedené nedostatky sa odstránia spósobom spracovania sulfldlcko-alkalického roztoku podlá vynálezu, ktorého podstata spočívá v tom, že sulfidlcko-alkalický roztok o koncentrácii 0,1 až 20 g.l“¹ arzénu, 2 až 30 g.l“¹ síry a 0,1 až 50 g.l¹sodíka sa oxiduje peroxidem vodíka za účelom oxidácle síry na síran a oxidácie trojmocného arzénu na pátmocný arzén, okyslí sa zriedenou kyselinou sírovou na hodnotu pH 1,5-4. Prídavkom oxidu vápenatého s 2 až ónásobným prebytkom stechiometrického množstva vápnlka vzhladom na obsah síry sa počas doby 60 min pri teplote 70 až 100 °C odstránl arzén z roztoku zrážaním až na deponovateťnú, sanitámu formu arzeničnanu vápenatého a hydroxidu vápenatého. Roztok s obsahom síranu sodného o koncentrácii arzénu menej ako 2 mg.l¹ sa dočistí prídavkom aíranu železnatého. Železo sa odstráni vo forme hydroxidu železitého a roztok o koncentrácii menej ako 0,6 mg.!^-} arzénu sa odpaří a vysuší, čímž sa získá predajný kryštalický síran sodný, ktorý je možné tepelnou úpravou v redukčných podmienkach previesť opat na sulfid sodný.The above-mentioned drawbacks are eliminated by the process for treating a sulfide-alkaline solution according to the invention, the essence of which consists in that the sulfide-alkaline solution with a concentration of 0.1 to 20 g / ^{l of} arsenic, 2 to 30 g / ^{l of} sulfur and 0.1 to 50 g of gl ¹ sodium is oxidized with hydrogen peroxide to oxidize sulfur to sulfate and oxidize trivalent arsenic to pentavalent arsenic, acidified to pH 1.5-4 with dilute sulfuric acid. The addition of calcium oxide with a 2- to 10-fold excess of stoichiometric amount of calcium relative to the sulfur content removed the solution from the solution by precipitation to a depositable, sanitary form of calcium arsenate and calcium hydroxide for 60 minutes at 70-100 ° C. A solution containing sodium sulphate with an arsenic concentration of less than 2 mg / ^l is purified by the addition of ferrous sulphate. The iron is removed in the form of ferric hydroxide and a solution with a concentration of less than 0.6 mg. ^The arsenic is evaporated and dried to give marketable crystalline sodium sulfate, which can be converted to sodium sulfide again by heat treatment under reducing conditions.

Výhodou podía vynálezu je spracovanie sulfidicko-alkalických roztokov po hydrometalurgickom spracovaní úletov z výroby médi tým, že sa z roztoku odstránl arzén pod koncentráciu 0,6 mg.l“¹ bez možnosti vzniku jedovatého sírovodíka. Navrhovaným postupom sa získá deponovateíná forma arzeničnanu vápenatého a predajný produkt síran sodný.An advantage according to the invention is the treatment of sulphidic-alkaline solutions after hydrometallurgical treatment of fly ash from the production of media by removing arsenic from a solution below a concentration of 0.6 mg.l ^-1 without the possibility of the formation of toxic hydrogen sulfide. The proposed process gives a depositable form of calcium arsenate and a marketable product, sodium sulphate.

Spoieob podťa vynálezu je popísaný v příkladech.The process according to the invention is described in the examples.

Příklad 1Example 1

Sulfidlcko-alkalický roztok po lúhování úletov z výroby médi o koncentrácii 1,72 g.l“¹ arzénu, 10,22 g.l“¹ sodíka a 4,84 g-1“¹ síry, hodnote pH 8,71 sa oxidoval peroxidem vodíka na hodnotu pH = 6,5. Okyslením roztoku kyselinou sírovou na hodnotu pH a 2,5 a zrážaním oxldom vápenatým v 4násobnom přebytku vápnlka vzhladom na obsah arzénu počas doby 60 min. pri teplote 90 °C, sa odstránl arzén do deponovateťnej zlúčeniny arzeničnanu vápenatého s prebytkom hydroxidu vápenatého s obsahom 23 % hmotnosti arzénu a 22,05 % hmotnosti vápnlka. Roztok po odstránení arzénu obsahuje síran sodný o koncentrácii 7,66 g.l“¹ síry, 11,55 g.l“¹ sodíka a menej ako mg.l¹ arzénu. Odpařením roztoku aa zíaka krystalický síran sodný. Tento sa podrobil tepelnej úpravě pri teplote 850 °C pri redukčných podmienkach a získal sa sulfid sodný, ktorý sa použil spat na lúhovanie arzénu z roztokov.Sulfidlcko-alkaline solution after leaching dusts from the production of copper concentration of 1.72 gl ^"1 of arsenic, 10.22 gl" ¹ and 4.84 g of sodium-1 'S ^1, a pH of 8.71 was oxidized with hydrogen peroxide at a pH of = 6.5. By acidifying the solution with sulfuric acid to pH 2.5 and precipitating with calcium oxide in a 4-fold excess of lime relative to the arsenic content for 60 minutes. at 90 ° C, arsenic was removed to a calcium arsenate depositable compound with an excess of calcium hydroxide containing 23% by weight of arsenic and 22.05% by weight of lime. The solution after removal of arsenic contains sodium sulphate at a concentration of 7.66 g / ^{l of} sulfur, 11.55 g / ^{l of} sodium and less than mg / ^{l of} arsenic. Evaporation of the solution a and crystalline sodium sulfate. This was subjected to heat treatment at 850 ° C under reducing conditions to give sodium sulfide, which was used to leach arsenic from solutions.

Příklad 2Example 2

Sulfidicko-alkalický roztok po lúhovaní úletov z výroby médi o koncentrácii 2,46 g.l’¹ arzénu, 10,44 g.l¹ sodíka a 4,96 g.l¹ síry, bodnote pH 10,08 sa oxidoval peroxidom vodíka na hodnotu pH 9,27. Okyslením roztoku kyselinou sírovou na hodnotu pH 2,5 a zrážaním oxidom vápenatým v 4násobnom přebytku stechiometrického množstva vápnika vzhladom na obsah arzénu počas doby 60 min pri teplote 90 °C, sa odstráni arzén do deponovatel'nej zlúčeniny arzeničnanu vápenatého s přebytkem hydroxidu vápenatého s obsahom 18,65 % hmotnosti arzénu a 24,75 % hmotnosti vápnika. Roztok po odstránení arzénu obsahuje síran sodný o koncentrácii 7,24 g.l¹ síry, 12,50 g.l¹ sodíka a menej ako 2 mg.l¹ arzénu. Na jemné dočistenie síranu sodného sa použije síran železnatý. Železo sa 2 roztoku odstraní vo forme hydroxidu železitého, koncentrácia arzénu klesne pod 0,6 mg.l¹ odpařením a kryštalizáciou roztoku sa získá krystalický síran sodný. Síran sodný sa spracoval podobné, ako je to uvedené v příklade 1«The sulphide-alkaline solution after leaching of the effluents from the production of media with a concentration of 2.46 g.l ^{-1 of} arsenic, 10.44 g / ^{l of} sodium and 4.96 g / ^{l of} sulfur, with a pH of 10.08, was oxidized with hydrogen peroxide to pH 9.27. By acidifying the solution to pH 2.5 with sulfuric acid and precipitating with calcium oxide in a 4-fold excess of the stoichiometric amount of calcium relative to the arsenic content for 60 minutes at 90 ° C, arsenic is removed to a depositable calcium arsenate compound with an excess of calcium hydroxide containing calcium hydroxide. 18.65% by weight of arsenic and 24.75% by weight of calcium. The solution after removal of arsenic contains sodium sulphate at a concentration of 7.24 g / ^{l of} sulfur, 12.50 g / ^{l of} sodium and less than 2 mg / ^{l of} arsenic. Ferrous sulphate is used for fine purification of sodium sulphate. The iron was removed from the solution as ferric hydroxide, the concentration of arsenic dropped below 0.6 mg / ^{L by} evaporation and crystallization of the solution gave crystalline sodium sulfate. Sodium sulfate was treated similarly to Example 1.

Příklad 3Example 3

Sulfidicko-alkalický roztok po lúhovaní úletov z výroby médi o koncentrácii 5,12 g.l¹ arzénu, 9,72 g.l“¹ airy a 21,88 g.l¹ sodíka, hodnote pH » 12,0 sa oxidoval peroxidom vodíka na hodnotu pH 10. Okyslením roztoku kyselinou sírovou na hodnotu pH 2,5 á zrážaním oxidom vápenatým so 4násobným přebytkem stechiometrického množstva vápnika vzhťadom na obsah arzénu počas doby 60 min pri teplote 90 °C, sa odstráni arzén do deponovatel'nej zlúčeniny vyššie popísaného zloženia s obsahom 15,62 % hmotnosti arzénu a 26,3 % hmotnosti vápnika. Roztok po odstránení arzénu obsahuje síran sodný o koncentrácii 14,14 g.l¹ síry, 25,6 g.l¹ sodíka a menej ako 1,5 mg.l¹ arzénu. Neutralizáciou roztoku kyselinou sírovou na hodnotu pH 7, odpařením a sušením sa získá kryštalický síran sodný o zložení 31,10 % hmotnosti sodíka, 21 % hmotnosti síry, 0,29 % hmotnosti vápnika a 0,015 % hmotnosti arzénu.Sulfide-alkaline solution after leaching of effluents from the production of media with a concentration of 5.12 gl ¹ arsenic, 9.72 gl ^-1 airy and 21.88 gl ¹ sodium, pH value> 12.0 was oxidized with hydrogen peroxide to pH 10. By acidification sulfuric acid to pH 2.5 and precipitated with calcium oxide with a 4-fold excess of stoichiometric amount of calcium relative to the arsenic content for 60 minutes at 90 ° C, the arsenic was removed to a depositable compound of the above-described composition containing 15.62% by weight of arsenic and 26.3% by weight of calcium. The solution after removal of arsenic contains sodium sulphate at a concentration of 14.14 g / ^{l of} sulfur, 25.6 g / ^{l of} sodium and less than 1.5 mg / ^{l of} arsenic. Neutralization of the solution with sulfuric acid to pH 7, evaporation and drying gave crystalline sodium sulfate with a composition of 31.10% by weight of sodium, 21% by weight of sulfur, 0.29% by weight of calcium and 0.015% by weight of arsenic.

Claims

2 mg.l -1 arsenic. Evaporation of the solution yields crystalline sodium sulphate. This was subjected to a heat treatment at 850 ° C under reducing conditions to give the sulfidium salt which was used to digest the arsenic from the solutions. Example

2 Sulphide-alkaline solution after leaching from the production of media with a concentration of 2,46 g / l arsenic, 10,44 g / l of sodium and 4,96 g / l of sulfur, pH = 10,08 was hydrogenated with hydrogen peroxide to pH 9.27. Acidification of the solution with a pH of 2.5 and precipitation of calcium oxide in a 4-fold excess of the stoichiometric amount of calcium relative to the arsenic content for 60 min at 90 ° C, removing the arsenic into the calcium arsenate depositing compound with an excess of calcium hydroxide and a content of 18.65 % by weight of arsenic and 24.75% by weight of calcium. The arsenic removal solution contains sodium sulphate at a concentration of 7.24 g / l sulfur, 12.50 g / l sodium and less than 2 mg / l arsenic. Ferrous sulphate is used for fine purification of sodium sulphate. it is removed in the form of ferric hydroxide, the concentration of arsenic falls below 0.6 mg.l -1 by evaporation and crystallization of the solution yields crystalline sodium sulfate. Sodium sulfate was treated similar to that described in Example 1. Example

3 Sulphide-alkaline solution after leaching from the production of medium with a concentration of 5.12 g of "1 arsenic, 9.72 g" of sulfur and 21.88 g of "1 sodium, with a pH of» 12.0 with hydrogen peroxide to a value of pH 10. Acidification of the solution with a pH of 2.5 with calcium oxide precipitation with a 4-fold excess of stoichiometric calcium relative to the arsenic content for 60 min at 90 ° C, removing the arsenic to a depositable compound of the above described composition containing 15.62. The arsenic removal solution contains sodium sulfate at 14.14 g / l sulfur, 25.6 g / l sodium and less than 1.5 mg / l arsenic. Neutralization of the solution with sulfuric acid to pH 7, evaporation and drying yields crystalline sodium sulfate of 31.10% by weight of sodium, 21% by weight of sulfur, 0.29% by weight of calcium and 0.015% by weight of arsenic. PATENT REQUIREMENTS A process for removing arsenic from sulphide-alkaline solutions from hydrometallurgical treatment of media from the production of a medium, characterized in that peroxide hydrogen is applied to the solution and, after oxidation, the pH of the solution is adjusted to 1.5 to 4 with acidic acid. up to 6 times the excess of stoichiometric calcium with respect to the arsenic content for 60 minutes at 90 ° C, the calcium arsenate precipitate is filtered off, dried and deposited, and the solution containing the marzene is less than 2 mg / l. after filtering off the ferric hydroxide, a solution of less than 0.5 mg.l -1 of arsenic is evaporated, dried and crystalline sodium sulphate is obtained which, by heat treatment at 800 to 950 ° C under reducing conditions, can be dropped to sodium sulphide.