Improvements in and relating to solid/fluid contacting

摘要

The ion exchange or charcoal purification and decolorization of a sugar solution is performed by counter-currently contacting the solids with the solution in a process comprising alternate periods of solids dispersion and substantially complete separation by settling, wherein solution moves through the system from one or more than one substantially wholly liquid-phase volume above the level of the dispersed solids, and solids move through the system from one or more than one substantially wholly solids-phase volume created by said settling.ALSO: Particulate solids are countercurrently contacted with a gas or liquid in a process comprising alternate periods of solids dispersion and substantially complete separation by settling, wherein fluid moves through the system from one or more substantially wholly fluids phase volume above the level of the dispersed solids, and solids move through the system from one or more substantially wholly solids phase volume created by said settling. The fluid flow may range from zero with maximum average solids flow to an average maximum corresponding to zero solids flow. The process may be applied to ion-exchange processes, e.g. for recovery of chromium and other metals from plating waste solutions, and of gold from leach solutions, to leaching coarse ground oxidized copper ore with sulphuric acid and to roasting pyrites minerals to produce sulphur dioxide, and Fig. 16 illustrates the application to recovery of U3O8 from an ore leach solution containing free H2SO4 to a pH of 1.8. The leach solution is fed by pump P1 to the second stage of five-stage column C1 and passes upwardly therethrough, being discharged at the top. Resin passes down from one of alternative tanks T1, T2 and is discharged from the last stage into a tank T3 or T4. The cycle referred to above is produced by means of a pump P2 the flow from which may be reversed by means of valves V1, V2. The resin containing uranium is then expelled by means of water into a tank T5 or T6 and thence passed to column C2 in which regeneration of the resin and recovery of uranium takes place by means of sodium chloride solution in the same way as in column C1.ALSO:Particulate solids are countercurrently contacted with a gas or liquid in a process comprising alternate periods of solids dispersion and substantially complete separation by settling, wherein fluid moves through the system from one or more substantially wholly fluids phase volume above the level of the dispersed solids, and solids move through the system from one or more substantially wholly solids phase volume created by said settling. The fluid flow may range from zero with maximum average solids flow to an average maximum corresponding to zero solids flow. The process may be applied to leaching, crystallisation, drying, adsorption, gas or liquid phase reactions employing solid catalysts and gas/ or liquid/solid reactions. Application to an ion exchange process is described in detail (see Division C1) and it is stated also to be applicable to purification of water in two stages using a cation exchange resin to remove Ca, Na and Mg and an anion exchanger for , and to the deionisation of dye solutions; roasting of pyrites and leaching of ground oxidised copper ore with sulphuric acid are also mentioned. Figs. 10-12 (not shown) illustrate three periods of a cycle involving reversal of flow. Fig. 10 shows a bed of solids dispersed by the fluid; in Fig. 11 the bed has settled; and in Fig. 12 backflow of fluid is transferring solid to the preceding zone. Several vessels of the kind shown may be linked in series to form a multistage contactor: it is also stated that a convoluted tube may be employed in place of the series of vessels. Fig. 1 (not shown) illustrates a four-stage contactor in which solids enter at 4 and are withdrawn at 11 whilst the corresponding inlets and outlet for fluid are 7 and 3. Pulses are applied by means of a generator 6 to a balancing leg 5 whereby the desired sequence takes place in the stages which are defined by imperforate dished supports for the solids, communication between the stages being obtained by conduits 8. Solids may if desired be fed to the first contacting stage as a slurry in the case of solid/liquid systems. Fig. 3 (not shown) illustrates another form of column element consisting of a bubble cap plate. Figs. 4, 13 and 15 (not shown) illustrate other forms of column contactors. In Fig. 13, during the first period, solids are dispersed above perforated plates 30 by means of fluid entering zones 42 of the contacting stages (defined by conical plates 38) through pipes 54. In the second period the solids come to rest on the plates 30 and a proportion pass therethrough. During the third period when the fluid flow reverses, solids are drawn in to spaces 50 and 42 and transferred downwardly through conduit 54 into the space 40 of the stage next therebelow. In Fig. 15, pairs 101, 102 of perforated plates serve to support the dispersed solids during upflow of fluid and permit settling without allowing solids to pass into the next lower chamber until the fluid flow is reversed. A valved bypass line 106 is provided whereby the amount of solids transferred can be controlled. Fig. 16 (not shown) illustrates a uranium extraction process using anion exchange resin (see Division C1) in a column of the type shown in Fig. 13, followed by regeneration with sodium chloride in a similar column. Figs. 17 and 18 (not shown) illustrate a pneumatic device for controlling the pulses to be applied to the gas or liquid and Fig. 19 (not shown) illustrates a control device employing valves to reverse the flow of a gas in a gas/solid contacing process.