Patent GB-456443-A (GB)
Title: Improvements in or relating to separators and washing apparatus for coal and other minerals
IPC: B03B13/00
Filed: 1935-02-04
Abstract: 456,443. Automatic control systems. FRANCE, A., 15, Rue Lambert Grisard, Liege, Belgium. Feb. 4, 1935, No. 3561. [Class 38 (iv)] [See also Group II] The discharge of dense products from a trough washer is made dependent upon the level of liquid in the trough, the control being effected through two electric circuits each comprising an electromagnet which electromagnets control the mechanical means for opening and closing the discharge outlet or outlets. The opening and closing of the electromagnet circuits is preferably effected by the opening and closing of or variation of current intensity in primary circuits containing relays. In the form shown in Figs. 2, 3, and 4 the trough 8 has one or more discharge devices 9, which may be of either of the types described in Specifications 142,735 and 269,017, [both in Class 82 (ii)], the opening of each of which is controlled by a lever I, Fig. 4, which is connected to a sliding block H through which passes a bar C which is continuously reciprocated and which has racks K J on its upper and under surfaces respectively. Pawls Land M, which can engage the racks JK respectively, are provided in the block H, the position of the pawls and therefore the movement of the block H and the lever I controlling the discharge outlet being determined by the opening and closing of two circuits of industrial voltage containing electromagnets N, O controlling the pawls L, M respectively. The opening and closing of these circuits is effected by the opening and closing of two primary circuits of low voltage containing relays T, S and also containing switch devices by which the opening and closing of these circuits is dependent on the level of liquid in the trough. In the form shown the switch device comprises a series of electrodes A1, A2, A3 &c., positioned at different levels in the trough, the electrode A1 being a single electrode and the remaining electrodes being double electrodes A2a, A2b, A3a A3b, &c. The electrodes A1, A2a, A3a, &c., are connected to contacts P1, P2, P3, &c. of a multiple contact switch, the electrodes A2b, A3b &c. being connected to contacts V2, V3 &c., on the same switch. The primary circuits are completed by means of brushes Q, R on the lever I which move over the contacts P1 P2 &c. and VI, V2, V3 &c. respectively and connect them to the relays S and T. The brushes Q and R are laterally displaced so that the brush R is in contact with V2 while the brush Q is in contact with P1. In operation if the level of liquid in the trough is such as to wet the electrode A1 but not the electrode A2 and the brush Q is in contact with P1 current passes through the relay S and closes the high voltage circuit containing the electromagnet O which raises the pawl M and allows the bar C to reciprocate without moving the block H and lever I. If owing to the accumulation of dense products the water level rises further and wets the electrode A2 the other electromagnet circuit is closed through the contact V2, brush R and relay T, the pawl N is raised and the block H and lever I move with the bar C and open the discharge outlet until the brush R passes off the contact V2. The discharge openings are closed when both the primary circuits are broken owing to the fall of the level of the liquid. The electrodes may be replaced by floats which actuate switches comprising mercury cups and a connecting member. In a modification Fig. 11 a float 17 in the trough may be used to vary the depth to which two electrodes Ax are immersed in a conducting liquid, the electrodes being connected to the contacts PI, P2, &c., V1, V2 &c., of the multiple contact switch through relays S1, S2 &c., T1, T2 &c. of different and variable sensitiveness so that the intensity of the current in the primary circuits controls the opening and closing of the electromagnet circuits. The electrodes may be immersed in the liquid in the trough and the float omitted A similar control may be effected in which the variation in the current intensity is produced by the use of a photo-electric cell.