摘要:
A method for treating a waste material (20) containing sulfuric acid and metal ions, as In the case of the waste material the production of the T1O2, provides mixing to the waste material (20) an alkaline reagent (10), selected among a hydroxide of an alkaline metal such as Mg, Zn, Sn, adapted to selectively precipitate (300) the cations as hydroxides, thus obtaining a first mixture (21) having a higher pH that contains a solution (22) of a sulfate and/or oxysulfate of the metal and solid hydroxides (23) of the metal cations that are separated from the first mixture (21) and can be used in metal sulfates production process. The method also comprises mixing the solution (22) with a precipitation agent (31), thus forming a second mixture (32) in which the sulfate and/or oxysulfate precipitates and is removed (301), heated, reduced and decomposed (400) by means of a reducing agent (41) selected among elemental sulfur, hydrogen and a reducing flame, thus obtaining SO 2 (42) available for making H 2 SO 4 , and a solid oxide (43) of the metal of the alkaline reagent that is recycled (101) as alkaline reagent (10) in the step (200) of mixing with the waste material (20). Advantageously, a step (350) is provided of recovering precipitation agent (31) from the water of second mixture (32), after removing (301) the sulfate and/or oxysulfate, and a step (351) is also provided of recycling the regenerated precipitation agent (31), In particular, an alcohol as ethyl alcohol, used as the precipitation agent (31), can be easily regenerated by distillation, exploiting low temperature-heat, which is largely available from a possible sulfuric acid production plant close to the plant that producing the sulfuric waste material (20). The method according to the invention makes it possible to eliminate the sludge resulting from the sulfuric waste material treatment, while recovering valuable compounds.
摘要:
The invention relates to a process for the production of chlorine dioxide in an apparatus comprising a reaction vessel holding a reaction medium and a circulation conduit leading through a heater for the reaction medium, said process comprising the steps of continuously: a) maintaining the reaction medium at subatmospheric pressure and a temperature sufficient for evaporating water; b) circulating reaction medium through the circulation conduit and the heater; c) reacting alkali metal chlorate, sulfuric acid and hydrogen peroxide in the reaction medium to form chlorine dioxide, oxygen and alkali metal sulfate; d) feeding alkali metal chlorate, sulfuric acid and hydrogen peroxide to the reaction medium, wherein the sulfuric acid is fed through an inlet into the circulation conduit and the hydrogen peroxide is fed through an inlet directly into the reaction vessel or through an inlet into the circulation conduit down-streams the inlet for sulfuric acid at a distance in the flow direction therefrom of at least about the inner diameter of the circulation conduit; and, e) withdrawing a gas comprising chlorine dioxide, oxygen and evaporated water. The invention further relates to an apparatus for the production of chlorine dioxide.
摘要:
Natriumhydrogensulfat wird durch Eintragen von Natriumchlorid oder Natriumsulfat sowie Schwefelsäure in geschmolzenes Natriumhydrogensulfat hergestellt. Die Schmelze wird beheizt und in dem Maß, in dem sie sich bildet, aus dem Reaktionsgefäß abgezogen. Die Ausgangsprodukte müssen mindestens teilweise vor dem Eintragen in die Schmelze vorgewärmt werden.
摘要:
La présente invention concerne un procédé de préparation d'hydroxyde de lithium comprenant de soumettre une composition aqueuse (A) comprenant du sulfate de lithium, et du sulfate de sodium, à une électrodialyse à membranes bipolaires; ladite étape d'électrodialyse à membranes bipolaires comprend le traitement sur un électrodialyseur comprenant au moins une cellule d'électrodialyse (200) comprenant un premier compartiment (220), alimenté en eau, et délimité entre une première membrane bipolaire (250) et une membrane anionique centrale (230), et un deuxième compartiment (210), alimenté par ladite composition aqueuse (A), et délimité entre ladite membrane anionique centrale (230) et une deuxième membrane bipolaire (240), puis de récupérer, de ladite au moins une cellule d'électrodialyse (200), une composition aqueuse (B) comprenant de l'hydroxyde de lithium et du sulfate de sodium, et la soumettre à une étape de cristallisation pour la préparation d'un sel.