GB696799A - Improvements in or relating to processing materials - Google Patents

Abstract

<PICT:0696799/IV (a)/1> A method of pulverizing wood shavings or other cellulosic materials consists in carrying them in a gaseous fluid and causing them to collide, and simultaneously subjecting them to the effect of "intense sonic energy," which is defined as including a sound energy which at least at some frequencies has an energy level in excess of 120 decibels (compared with a datum of 0.000204 dynes per square centimetre) and in which the frequency ranges from the low audible through, and including, the ultrasonic. The shavings are carried in air or other gas according to the degree of oxidation desired of the resinous constituents, or the oxidation can be controlled by adding neutralizing, wetting or coating materials to the gaseous medium. The temperature, pressure and humidity of the gaseous medium may also be varied to control the operation. Apparatus for use in the method comprises a casing 11, Fig. 1, which has one or more inlets at the foot for the gas and shavings and is provided with a central driven shaft 20 carrying a series of superposed stages of radial blades 45, 47, 49 with interposed discs supported either from adjacent blades or directly from the shaft. The construction and mounting of the discs are such that the gaseous flow sets them into vibration to produce the intense sonic energy defined above, and this effect may be augmented by arranging also for the radial blades, or the edges thereof, to vibrate. Alternatively only the radial blades may vibrate, the discs being either dispensed with or made non-vibrating. The casing 11 is provided in the region of the radial blades and discs with a fluted lining 40 of hard material or soft rubber; the lower part of the lining may be of harder material than the upper part. After passing the uppermost stage of radial blades, the material passes to a classifier in the form of a fan blade 28 on the shaft 20 and is then discharged through an opening 29 to a chamber 15, where further blades 37 eject it through an outlet 34. The diameter of successive stages of radial blades may first gradually increase and then gradually decrease. In some cases, Fig. 16 (not shown), the gaseous fluid may be arranged to circulate in a closed circuit under pressure or vacuum; heat-exchanging means may be provided in the circuit and the processed material may be withdrawn at a suitable point in the circuit. The operation in the casing 11 may be effected under the influence of light either inside or outside the visible range.ALSO:<PICT:0696799/III/1> Solid materials are pulverized and at the same time subjected to a chemical reaction or coated by carrying them in a dry or nearly dry gaseous fluid and causing them to collide and simultaneously subjecting them to the effects of "intense sonic energy" which is defined as including a sonic energy which at least at some frequencies has an energy level in excess of 120 decibels (compared with a datum of 0.000204 dynes per sq. cm.) and in which the frequency ranges from the low audible through, and including the ultrasonic. The gaseous medium may be air, nitrogen, dry or nearly dry steam, bromine, chlorine, hydrogen, carbon dioxide or helium, or a mixture of such gases, and the temperature, pressure and humidity of the medium may be varied to control the operation. Suitable solid or liquid catalysts and reactants may be added to the solid and/or gaseous materials flowing into the treating chamber. Acid or base materials in liquid or gaseous form, such as H2SO4, H3PO4, HCl, SO2, SO3, or NH3 may be added to the inflowing materials; this process is applicable to the conversion of cellulose fibres to starch by pulverization in the presence of H3PO4, the processing of phosphate-containing rocks in the presence of HCl, the hydrolysis of starch to sugar, and the caramelization of sugar or milk powder. Sugar together with solid surface-active compounds may be fed into the treating chamber to produce coated sugar particles. The invention may also be used to apply a coating of plastics or dye to particles such as sulphur, Glauber's salt, gypsum, graphite, clay, novaculite, vermiculite, mineral dyes, and abrasives. Apparatus for use in the method comprises a casing 11, Fig. 1, which has one or more inlets at the foot for the gas and solid materials and is provided with a central driven shaft 20 carrying a series of superposed stages of radial blades 45, 47, 49 with interposed discs 52 supported either from the adjacent blades or directly from the shaft. The construction and mounting of the discs are such that the gaseous flow sets them into vibration to produce the intense sonic energy defined above, and this effect may be augmented by arranging also for the radial blades, or the edges thereof, to vibrate. Alternatively, only the radial blades may vibrate, the discs being either dispensed with or made non-vibrating. The casing 11 is provided in the region of the radial blades and discs with a fluted lining 40 of hard material or rubber; the lower part of the lining may be of harder material than the upper part. After passing the uppermost stage of radial blades, the material passes to a classifier in the form of fan blades 28 on the shaft 20 and is then discharged through an opening 29 to a chamber 15 where further fan blades 37 eject it through an outlet 34. The diameter of successive stages of the radial blades and discs may first gradually increase and then decrease. In some cases, Fig. 16, (not shown), the gaseous fluid may be arranged to circulate in a closed circuit under pressure or vacuum; heat-exchanging means may be provided in the circuit, and the processed material may be withdrawn at a suitable point in the circuit. The operation in the casing 11 may be effected under the influence of light either inside or outside the visible range.