Norsk Hydro, A.s.

Glor T Mejdell

Kjell W Tveten

Sven Arne Kjolberg

Kjell O Loiten

Jan B Marcussen

Odd E Palmgren

Karl J Giskehaug

Hanne M Baumann

Bjarne Vik

Arne Talmoen

Process for production of magnesium chloride with sufficient purity for the production of magnesium metal, by leaching a magnesium containing raw material in hydrochloric acid. It is essential to keep the ratio between acid soluble iron and nickel greater than 120 and the ratio between acid soluble iron and phosphorus greater than 20 in the primary magnesium chloride solution, to obtain a sufficiently pure product. The acid soluble iron can partly or completely be substituted by an equal, molar amount of acid soluble aluminium. It is especially preferred to use mixtures of macro- and crypto-crystalline magnesites in the ratio 1:10-10:1 as raw material.

Process for production of magnesium chloride

Method for production of magnesium chloride, to be used for production of magnesium, by leaching of magnesite in hydrochloric acid. A two-stage leaching process is used where in a first reactor magnesite lumps are dissolved in hydrochloric acid. The magnesium chloride containing solution is led to a second reactor, where finely ground magnesite or hydrochloric acid is added to obtain approximate equivalence between magnesium and chlorine. To precipitate the impurities an excess of magnesium oxide or magnesium hydroxide is added in one or several purification stages.

Method for production of magnesium chloride

The invention relates to a method and apparatus for enriching compounds almost insoluble in water, particularly chlorinated hydrocarbons, and thereby removing them from aqueous suspensions of solid particles contaminated by such compounds. The aqueous suspension is brought in contact with an organic hydrocarbon containing solvent, and the suspension is extracted with the organic solvent in one or more mixing stages with subsequent phase separation. Each stage comprises one or more mixing sequences in series arranged upstream of a phase separation and from where a substantial part of the organic solvent is recirculated to the first mixing sequence within that stage. The invention secures nearly complete leaching of compounds present in even less than 10% of other solid particles in an aqueous suspension.

Method and apparatus for enriching compounds of low water solubility

The present invention relates to a process for the reduction of the vinyl chloride content of aqueous dispersions of vinyl chloride polymers and copolymers by counter-current stripping with steam in a perforated plate column, by (1) adjusting the amount of steam introduced at the bottom of the column in such relation to the perforated area of an individual plate that the pressure drop across one plate gives a steam space between two adjacent plates of not more than 50 mm in height, such that the steam space is established just underneath the upper perforated plate and whereby the liquid layer is maintained above the lower perforated plate, and the liquid by bubbling steam therethrough, flushes the wall (surfaces) of the column in the steam space and said perforated plates to become clear of polymer particles; (2) the amount of dispersion fed to the top of the column and the amount of outgoing, stripped dispersion are adjusted in such relation to each other that at any time, the liquid layer is maintained well above the downcomer of the uppermost perforated plate; and (3) above the liquid level and the level at which the dispersion is fed, a liquid is introduced which continuously or discontinuously flushes the wall of the column.

Process for reducing the vinyl chloride content of aqueous dispersions

Aluminate mother liquor is passed countercurrent to the direction of feed of aluminum hydroxide crystals through at least two stages, each of which has a lower turbulent zone with a high suspension density and which is agitated under conditions which assure particle growth via crystal growth and an upper non-turbulent, stagnant liquid layer from which most crystals settle back into the respective lower turbulent zone. The suspension density in the stages is maintained at a constant level by sending crystal suspension from the lower turbulent zone in all the precipitation stages but the first to the preceding stage. Mother liquor is removed from the upper stagnant zone of all stages but the last stage and sent to the respective following stages. Coarse crystal suspension is removed from the turbulent zone of the first stage for separation of the crystals for further processing, while the mother liquor is returned to the system.

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Porsgrunn, Norway

Glor T Mejdell