GB965182A - Improvements in or relating to granular material conditioning method and apparatus - Google Patents

Abstract

965,182. Photo-electric controls; testing caking; weighing apparatus. HARRY W. DIETERT CO. Jan. 16, 1962 [Jan. 16, 1961], No. 1618/62. Headings G1A, G1S and G1W. [Also in Divisions B1, B2 and B3] A method of conditioning granular material such as foundry sand, mortars, ceramics and welding rod flux material comprises continuously mulling the material during addition of an ingredient which affects its mouldability, measuring the varying mouldability of the material during continued mulling and addition of the ingredient, and terminating the addition of the ingredient when the mouldability of the granular material reaches the required value. Foundry sand is mulled in a muller 10 to which water may be added from a main 24 having a large valve 26 and a small valve 28. An outlet 30 from the muller allows samples to be supplied to a separator 35 comprising a vibratory riddle 36 above a tray 38. The riddle is formed of or coated with polytetrafluoroethylene to prevent sticking of the grains thereto. A comparison of the quantity which falls through the riddle on to the tray 38 with the quantity which remains on the riddle gives an indication of the mouldability of the sand. The respective quantities fall on to inclined slides 56, 58, which are pivotally mounted at 60. A greater amount falling through the screen on to the tray 38 and hence on to the slide 56, indicating a higher degree of mouldability causes the slides to tilt anticlockwise, causing an electronic control circuit to open the large valve 26 to supply water to the muller. As mouldability decreases a higher proportion of sand stays on the screen and is delivered to the slide 58, causing the slides to tilt clockwise. A first result due to a snap-over switch 96 closes the valve 26 and opens the smaller valve 28 to cause a reduced flow of water to the muller and then as the desired mouldability is reached an opaque member 90 is interposed between a light source 89 and a receiver 83 to stop the flow of water completely. The addition of additives other than water may be controlled. The operation of the slides may be adjusted to give a predetermined mouldability by variation of a weight. In a modification the movement of the slide regulates through an electro-pneumatic transducer a water-proportioning valve.