Patent GB-1475881-A (GB)
Title: Treatment of minerals
IPC: C04B33/04
Filed: 1973-03-19
Abstract: 1475881 Separating mixtures of mineral components; mixing apparatus ENGLISH CLAYS LOVERING POCHIN & CO Ltd 18 March 1974 [19 March 1973] 13174/73 Headings B1C and B2H [Also in Division Cl] At least one component is separated from a mixture of mineral components by (a) dispersing the mixture of mineral components in water to form an aqueous suspension containing 10-60% by weight of said mixture, (b) passing the suspension to an in-line mixer after adjusting solids content to not more than 20% when it is mixed with a non-polar organic liquid in which an anionic collector for at least one of the components has been dissolved or suspended, the volume ratio of said suspension to organic liquid being in the range 1-9:1, said mixing being effected under conditions such as the total amount of energy dissipated is 3-30 x 10<SP>4</SP> joules/Kg of the dry mixture, the total time taken to dissipate said energy does not exceed 8 minutes and one liquid is uniformly dispersed in the other but a stable emulsion is not formed, whereby at least one component of the mixture becomes concentrated in the interface and the remaining component(s) become concentrated in the aqueous phase, (c) discharging the mixtures from the mixer (d) separating or allowing to separate, the two liquid phases and (e) recovering at least a portion of the organic liquid and recycling. The dispersion of the mineral component in step (a) may be assisted by changing the pH to at least 8.0 or by addition of a defloculating agent such as a sodium silicate or a water-soluble organic macromolecular material having a number average molecular weight in the range 700-10000, examples of which are specified. Suitable organic liquids are kerosene, petroleum spirit, benzene, dichloroethane, CCl 4  and tetrabromoethane. The anionic collector may be a fatty acid or a soap having 10-20 C atoms, e.g. oleic acid or a sulphonated petroleum hydrocarbon and is typically used in amounts of 0.5-2.0 g/Kg of the mixture. The ratio of the two liquids is suitably 1-6:1, most preferably 2:1. The liquids may be mixed continuously in a mixer provided with a turbine rotating at a speed in the range 500-2500 rpm and a peripheral speed in the range 200-1200 m/min. Mixing is preferably continued for 2-6 minutes. Further water may be added to the mixture as it leaves the mixer. The aqueous phase which contains the purified mineral may be subjected to one or more further separation stages to allow any entrained non-polar organic liquid to separate. The organic liquid is preferably centrifuged to extract any solids and is then recycled. The process is particularly applicable to the treatment of kaolinitic clay (Examples 1-2) but may also be used for purifying strontium sulphate (Examples 3-4) or producing a ceramic flux material from a pegmatite (Example 5). A mixer used in the treatment comprises a box 36 of square cross-section having a flat plate 37 fixed across each of the four corners perpendicular to the bottom of the box to define an inner compartment of octagonal crosssection, a baffle 38 extending radially inwards towards the central vertical axis of the box at each of the eight angles of the octagon, V notches 39, 40, at the bast of each of the plate 37 and baffles 38 respectively. An impeller 41 is provided with a vertical shaft 42 carrying at its lower end a horizontal disc 43 to which are attached four blades 44 on the upper surface and four blades 45 on the lower surface, the blades being equally spaced on the disc. An aqueous suspension is introduced through conduit 46 and a non-polar organic liquid through conduit 14 and these are combined at a T-piece 47 and passed into the mixer 10 via a conduit 48. The mixture leaves the mixer 10 through a conduit 49 beneath the impeller. The depth of the liquid mixture in the mixer 10 may be monitored by a control device 50.