IMPROVED GOLD SAYING APPLIANCE.

Greymouth Evening Star, Volume XXXI, 13 August 1901, Page 3

IMPROVED GOLD SAYING APPLIANCE.

Mr James Simpson, dredging engineer ■applies us with the following circular which has been lodged at the Patent office in Wellington:— Specification of oscillating counterbalanced combined screen and conveyor, for use on gold dredges. Screen is flat-bottomed, and of any desired length and width, is mounted on pivots and made to oscillate by means of cranks and connecting rods. Screen may have one, two or more perforated bottoms or sieves (two preferably, as it doubles the capacity). The bottom may be straight from end to end or stopped for the quicker discharge of the gravel, etc. Sieves made of removal perforated plates, which can be replaced easily when worn. Perforations in plates may be of any required size or shape that may be found desirable, but larger in the upper sieves than the lower.

Screen may be set at any desired angle or pitch, and the hangers so arranged that the pitch can be altered at any time. Screen discharges the rough gravel and stones over its lower end into the conveyor, and the water, fine gravel and sand through the perforations on to an inclined sluice box, which is dressed with matting ripples or other gold-saving materials; the said matting is fastened to movable false bottoms let into the side of sluice box so that they can be drawn out for the purptse of washing the mats and cloths: (this sluice box catches thorough gold). A number of fine perforated plate* are placed at the lower end of sluice box, which allows water and very fine sand to pass through, and passes the rougher stuff over the end into a sieve placed in the lower bottom of the conveyor. Conveyor is made similarly to the screen, and made to oscillate in the opposite direction to the screen by means of a walking beam or orosshead pivoted in the centre, one end of it attached to the screen and the other to the conveyor. This arrangement forma a counterbalance, for when the screen is moving down carrying the stuff with it, the conveyor is moving up, leaving the stuff behind. The top and of the conveyor is made slightly larger than the screen to work into and discharge stuff without spilling. A number of fine perforated plates similar to those in the tail end of sluice box, are placed in the bottom of the conveyor at the top end to receive gravel discharged over the sluice box, and screen it and pass the rough stuff on into the ■ conveyor ; this sieve ia covered by an inclined plate which receives and passes on the stones and rough gravel discharged by the screen into the conveyor ; the bottom of the conveyor may be stopped and supplied with ripple bars to oatoh any nuggets that may have escaped the over the screen. The conveyor discharges stones, etc. through a shoot into the elevators, etc. The water and fine sand after passing through the sluice box and fine sieves falls into a hopper fixed on top of a cauldron.

Cauldron is a deep square box, into which all the water and sand from the screen passes; it is fitted with a number of midriffs, under and over which the water and sand pass, being kept thoroughly mixed by the agitation caused by the fall and force of the water; the outlets from the cauldron being lower than the inlet causes a current to pass through it, which prevents choking. A number of

dhannels pass from the outlets to spreaders, thence to the tables, by which means each table is supplied with an even sample of stuff to treat. The quantity can be regulated or shut off entirely by means of stoppers at the outlets. To clean out the cauldron or increase the current two or more pipes may be led from the water supply pipe into the bottom of the cauldron.

The screen itself without the conveyer or cauldron may be used with advantage on existing dredges which would not have room for the entire outfit. The outfit could be applied to sluicing.