WO1986006005A1

WO1986006005A1 - Mechanical prospective pan

Info

Publication number: WO1986006005A1
Application number: PCT/BR1986/000002
Authority: WO
Inventors: Murilo Luciano; Augusto Luciano
Original assignee: METRO - EQUIPAMENTOS PARA MINERAÇA^ñO LTDA.
Priority date: 1985-04-09
Filing date: 1986-02-21
Publication date: 1986-10-23
Also published as: EP0218600A1; BR8501660A; AU5543686A

Abstract

The present invention is to be used in prospecting areas as a substitute for the manual pans, short and long sluices, lined with coarse fabric, for the collection of precious metals, with the purpose of making the prospecting areas economical, with a productivity equivalent to that of 60 men, which may be assigned to new prospecting areas, with the main prospecting pan (1) providing a counter-turning movement with the same turning speed on its shaft (5) and which maintains the pan (1) stationary while gravitates and oscillates around the fulcrum (6); the prospecting pan (2) is maintained stationary by the action of two counterweights (19), located 180o to each other, and for the removal of the water and of the final portion of the concentrate which contains free gold, cassiterite, etc., the prospecting pan (1) has, close to the bottom a plug (20) to which a clear plastic hose is connected, being provided, further, the adaptation of a removable auxiliary prospecting pan (2) at the center of the main pan (1) to which it is connected by four supports (18). The super concentrate obtained at the end of the auxiliary pan presents a recovery of 97% of the gold content of the mineral.

Description

"MECHANICAL PROSPECTIVE PAN" The present invention is related to a mechanical prospective pan with the object of obtaining a super- concentration of valuable metals and minerals such as Gold, cassiterite, etc; in the bowl of the pan.

The use of hand pans, short- and long sluices lined with coarse fabrics in prospecting areas, for the prospection and concentration of precious metals are widely known. About 90% of the work for extracting metals is done by hand what makes the process too expensive. Very seldom, mechanical dredges are used, and only by mining companies in their gold, cassiterite and diamond areas; most of the existing dredges in use are of suction type, operated by divers who collect the gold and cassiterite deposited in cavities in the bottom of the rivers.

So, one of the main advantages for using this mechanical pan is to make the operations in prospective areas more economical with a productivity equivalent to that of 60 men, who may be assigned to new prospecting areas, thereby increasing the national production.

The present invention, as per several tests performed with its prototypes, gives spectacular results at the separation of metal particles, such as gold, silver cassiterite (tin) , etc, which produces as important increase in the production of metal's. contained in the minerals derived from primary and secondary deposits.

The prospecting pan comprises a counter-rotation movement of the pan, with the same turning speed on its shaft, which mantains it stationary while it gravitates and oscillates around the fulcrum.

Upon the end of the treatment of a portion of mineral, with the prospecting pan halted, a concentrate of about 8 litres remains in the bottom of the pan, with high proportion of hematite, cassiterite and other heavy metals, including gold, existing in the ore. From this concentrate the gold particles are extracted through a hand pan or by amalgam.

In order to eliminate the use of the hand pan and the amalgam for recovering the gold particles contained in the concentrate, this invention was developed with the objective of producing a super-concentrate of high gold content. In order to obtain good results from the present invention the installation of 2 (two) counter-weights located 180° one in relation with the other is necessary to prevent the rotation of the pan on its axis, maintaining it stationary while gravitating and oscillating around the fulcrum. Other necessary device is the installation of an auxiliary removable pan, 650 mm in diameter to the center of the main prospecting pan of 1200 mm diameter, with such auxiliary pan having a border 54 mm high, provided with four supports, 90 one from the other, and located about 70 mm above the inverted vertex. In such a way it is possible to obtain a super concentration of the concentrate removed from the bottom of the prospecting pan, in order to extract the valuable metals in the specific case of auriferous mineral, with the retention of all valuable particles. A plug is located close to the bottom of 1200 mm diameter prospecting pan, to which a transparent plastic hose is connected for discharging the primary concentrate in a quick and safe way. As an alternative, the concentrate can be removed by suction. For the illustration of this report, and for allowing a better understanding ofthe novelty of the present invention, drawings are attached, where:

- Figure 1 shows an elevation of a preferred arrangement of the invention and its operating positions; - Figure 2 shows a plan of the mechanical prospecting pan shown on 1 and its operating positions;

- Figure 3 shows an elevation of the above machine with the auxiliary pan in its operating positions; and

- Figure 4 shows a plan of the machine in its operating positions.

As may be seen from figures 1 and 2, the mechanism of the mechanical prospecting pan comprises: an- oscillating steel plate conic surface (3) , provided with an upper edge (4) , connected at the end of a steel shaft (5) , which turns around an oscillating fulcrum (6), formed by a special double-row self compensating ball bearing, providing a gravitational paraboloid movement to the prospecting pan (1) around a vertical axis (7) . Said shaft (5) is adjusted at its lower portion, to an oscillating bronze bushing inserted into an adjustable radius eccentric (.8) which determines the working angle of the schaft (5) . As result of a counter- rotation movement, with the same turning speed relative to its shaft, the prospecting pan mantains itself stationary while it gravitates and oscillates around the fulcrum (.6) . The power transmission system comprises a shaft (9) a bearing (10) a coupling (.11), a speed reducer (.12) and an engine (13). At the lower portion of the prospecting pan (1) there is a ring-shaped channel (14) connected to two discharging channels (15) and (16) , through which the used water and the sterile material are discharged. At the upper part there is the shower nozzle (17) connected to a tank which may be filled by a manual or a mechanical pump from a well or a decanting tank for the recycling of the used water, when there is a shortage of this liquid.

The ring-shaped channel (14) collects, continuously, the water impregnated with sand and sterile material in suspension, which is rejected at point "A" which changes, its position, continuously, because it gravitates around the fulcrum (6) .

After lubricating and adjusting the engine speed and the gravitation distance around the fulcrum, as per the material to be concentrated, the engine is connected and the water opened, in a quantity sufficient for the volume of material to be washed. In the 1200 mm diameter prospecting pan the feeding may be continuous, by using a conveyor belt or 60 kg per minute of material, previously sifted in 4 mm screens. Upon falling into the prospecting pan (_.1) , the material is dragged in a spiralled swirl rotating, violently, in circles which become wider and wider, until it is discharged over the edge (4) of the points "A" of its course. The light and water soluble materials such as clay, lime, sand and other materials with low specific weight are dragged by the water and deposited, through the channels (14) (15) and (16) in piles or wagons, on both sides of the machine, with the water being possibly recycled. The material with specific weight above 5, remain rotating in the bottom of the pan (1) , retaining all gold particles contained in a mineral or alluvional sand. From this concentrate the gold particles can be extracted by a manual pan or by amalgamation or, better, by means of the auxiliar 650 mm diameter pan (2), as described below.

According to figures 3 and 4, which integrate the present invention, it is seen that four supports (18) o-f the auxiliary pan (2) are fitted on the edge (4) of the main prospecting pan (1) , with this main prospecting pan (1) being maintained stationary by the action of two counterweights (19) located 180° to each other; and close to the bottom of the pan there is a plug (20) to which a clear plastic hose is connected (not shown) , for the removal of water and the final portion of the concentrate containing free gold.

The concentrate obtained in the main pan (1) , at the end of the treatment of a lot of mineral, is removed through the plug (20) and then fed by hand to the auxiliary pan (2) , together with about 10 to 15 litres of water per minute.

Once the machine starts working again, the main pan

(1) transmits to the auxiliary pan (2) its paraboloid gravitational movements through, as said above, the four supports (18) fit to the edge (4) of the main pan (1) . In about 12 minutes all concentrates, approximately

3 8 dm in volume, 16 to 18 kg according with the mineral

3 contained, shall be passed again and 0,5 to 1,0 dm of a highly concentrated material will be retained in the bottom of the auxiliary pan, where 96 to 97% of the gold originally contained in the mineral will be present.

Treating 4 tons of auriferous mineral having an apparent specific weight of 1.6 gr/cub cm and a gold content of 2,0 grs/cub.meter, in one hour the volume treated in the main pan will be 2,5 cub.meter, or 2500 litres. Considering a volume of concentrate of 8 litres in the main pan the concentration efficiency will be 2500/8 = 312,5 parts to 1, with a gold retention of approximately 96% say 4,8 gr. Repassing the 8 litres of concentrate, containing

4,8 gr of free gold on the auxiliary pan, a concentration efficiency of 3,333 parts to 1 (volume treated in the main pan of 2500 litres/average final volume retained in the secondary pan of 0,75 litre) with a concentrating efficiency of 96%, -obtaining therefore 4.61 gram of gold that can be separated from the impurities of the concentrate by pyro etallurgy, straight in the crucible, without the use of amalgam, which presents serious risks for the human health and the ecology. We have no knowledge of the existence of any equipment for the gravimetric concentration of heavy metal particles, either electric, mechanical, vibratory, centrifugal, floating or stationary, which gives such an outstanding performance, either as for the reduction of the volume of the final concentrate or as for the content of metal particles - of coarse and very fine granulometry which reaches in the present invention about 96%.

Claims

1 - MECHANICAL PROSPECTING PAN, characterized by a main pan (1) comprising a conical surface (3) made of steel plate, provided with an upper edge (4) , connected to the end of an inclined shaft (5) , which rotates around an oscillating fulcrum (6) , formed by a special double-row ball bearing; a vertical axis (7); an eccentric (8) with adjustable radius; a shaft (9); a bearing (10), a coupling (11); a speed reducer (12) ; an' engine (13) ; a ring shaped channel (14) ; discharge channels (15) and (16) a shower nozzle (17) ; two counterweights (19); a plug (20) and an auxiliary pan (2).

2 - MECHANICAL PROSPECTING PAN,as per claim 1, ^" above, characterized by the fact that the prospecting pan (1) is maintained stationary while it gravitates and oscillates around the fulcrum (6) , by the action of two counterweights (19) located 180° one in relation to the other; and by the fact that to remove the water and the final portion of the concentrate which contains free gold and other valuable metals, the prospecting pan CD has,_, close to the bottom a plug (20), to which a clear plastic hose is connected.

3 - MECHANICAL PROSPECTING PAN, as per claim 1, characterized by the fact that the removable auxiliary pan (2) is provided with four supports (18) which are fitted on the edge (4) of the prospecting pan .(1) .