摘要:
The invention uses a stack of three compartment electrodialysis cells in a process for the production amino acid hydrochloride and an alkali. The electrodialysis cell contains bipolar, cation and anion membranes which are arranged to form acid, base and salt compartments. The process begins with supplying a salt solution to the salt compartment, water to the base compartment, and a liquid comprising an amino acid to the acid compartment. Preferably, the feed salt is sodium chloride or potassium chloride or lithium chloride. A direct current driving force is applied across the cell to convert the salt solution to an alkali in the base compartments and an amino acid hydrochloride in the acid compartment. The acid and alkali solutions and a depleted salt solution are withdrawn from their respective compartments. A chelating agent may be added to the salt solution before it is fed into the electrodialysis cell.
摘要:
The specification describes a process for pelletising particles of an alkali metal ferrite with an aqueous binder such as a black liquor derived from pulping wood chips. The particles are ground and fed to a microgranulator in measured quantities together with measured quantities of aqueous binder. The particles are ground such that they have an even size distribution about a mean in the range from 25 to 50 microns. The particles are mixed with the binder in the microgranulator to form microgranules which are fed to a pelletising pan. The temperature of the microgranules on the pelletising pan is controlled by cooling either or both the alkali metal ferrite or aqueous binder prior to measuring them into the microgranulator. A pan temperature of less than 70.degree. C. is disclosed.
摘要:
In minimizing effluents from a cellulose pulp mill, liquid effluents from a bleach plant are concentrated, and then incinerated to produce a residue including sodium, sulfate, and sodium chloride. This residue is distilled with sulfuric acid to produce gaseous hydrogen chloride and remaining residue, the HCl being used in chloride dioxide production for the bleach plant, while the remaining residue is passed to the recovery loop (e.g. recovery boiler). Sulfur containing gases from the non-condensible gas system may be combusted to produce gaseous sulfur dioxide, which is then converted to sulfuric acid, to distill the residue. Where a non-chlorine bleach plant is provided, the liquid effluents may be concentrated in evaporators and then passed directly to the recovery boiler. The liquid streams in the mill are managed by a cascade principle to reserve the cleanest water for only those processes where it is needed while minimizing its use where it is not necessary.
摘要:
An alkaline solution containing mercaptides is regenerated in an improved process wherein the alkaline solution to be regenerated containing a suitable oxidation catalyst is contacted with an oxygen-containing solvent which is immiscible with said alkaline solution in a reaction zone comprising a plurality of fibers positioned longitudinally within a conduit, whereby the two liquids are in contact while concurrently flowing through said reaction zone during which the mercaptides contained in the alkaline solution are oxidized to disulfides and are simultaneously extracted from the alkaline solution into the solvent solution.
摘要:
There is provided a process for preparing caustic soda solutions from naturally occurring alkaline minerals comprising double salts of sodium carbonate and calcium carbonate. The process comprises heating said naturally occurring alkaline minerals to temperatures sufficient to dehydrate and partially decarbonate said alkaline minerals and provide an intermediate product of a mixture of sodium carbonate and calcium oxide. This intermediate then is contacted with water to effect causticization of the sodium carbonate and provide a recoverable phase comprising an aqueous solution of caustic soda.
摘要:
The invention relates to an improvement in a method of regenerating alkaline or alkaline earth metal oxides or hydroxides from solution particularly in delignification processes wherein a suitable transition metal such as ferric oxide is burnt with the solution to produce a mixed oxide that is subsequently treated in hot water to regenerate the alkaline or alkaline earth metal oxide or hydroxide and precipitate the transition metal oxide. The improvement controls the presence of fines in the transition metal oxide to maintain these at an acceptable level in the fluidized bed combustion zone. This is achieved by contacting the fines with spent liquor from a delignification process. The invention also provides for the pelletization of the fine material of the transition metal oxide and spent delignification liquor can be used as a binder in the formation of such pellets.
摘要:
In the regeneration of alkaline liquors as used in paper pulping, a mixed oxide compound of an alkali or alkaline earth metal oxide and an oxide of Ti, Fe, Co, Ni, or Mn is formed by burning black liquor. The burning step is carried out in a fluidized bed. The mixed oxide product is washed in cold water and subsequently treated with hot water to precipitate the oxide of Ti, Fe, Co, Ni or Mn and enable recovery of the alkaline solution for recycling.
摘要:
Sodium sulfide or sodium hydrosulfide is oxidized to form sodium polysulfide and sodium hydroxide which may be further oxidized to sodium thiosulfate and sodium hydroxide. The oxidant is air, oxygen or oxygen in mixture with other gases, the reductant is aqueous sodium sulfide or sodium hydrosulfide and the reaction is carried out with both reactants in non-flooded contact with a solid catalyst material, of which a typical example is a particulate carbon treated with polytetrafluoroethylene (PTFE). The reaction is typically conducted at atmospheric pressure and without the application of heat, with the oxidant and the reductant being in interfacial contact with each other, but only, insofar as possible, at sites where both are simultaneously in contact with a catalyst which is prevented from being flooded by either the oxidant or reductant.
摘要:
Stable bipolar membranes of high permselectivity and low potential drop are prepared using either an anion or cation preformed first layer upon which a second layer or coating of an ion exchange resin of the opposite charge carried in a matrix polymer is applied. The second layer may be suitably applied such as by casting as a slurry of the ion exchange resin in a solution or by laminating a layer comprising a dispersion of the resin in a solid or fused polymer. Optionally, the surface of the first layer may be treated to increase the resin concentration and/or bonding at the interface, such as by sanding, etching, etc.
摘要:
Potassium is recovered as a dilute KOH solution from residue solids resulting from conversion of manganese ore to K.sub.2 MnO.sub.4 by reacting the solids with a Ca(OH).sub.2 under specified conditions. The resulting KOH solution can be returned to the K.sub.2 MnO.sub.4 plant and the solids of reduced potassium content are suitable for disposal in a landfill.