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close this book Tools for Mining
close this folder Technical Chapter 15: Gold Benefication
View the document 15.1 Amalgam press
View the document 15.2 Amalgamating table
View the document 15.3 Amalgamating barrel
View the document 15.4 Rocker, cradle
View the document 15.5 Mechanized, compact gold processor
View the document 15.6 Hydraulic gold trap
View the document 15.7 Retort for, amalgam
View the document 15.8 Centrifugal separator
View the document 15.9 Gold pan, batea
View the document 15.10 Jigs with jig bed, russel jig
View the document 15.11 Gold leaching
View the document 15.12 Gold separation by smelting
View the document 15.13 Gold-coal-agglomeration

15.9 Gold pan, batea

Gold Mining

Beneficiation, Gold Beneficiation

germ.:

Sichertrog, Waschpfanne, Schiffchen, Niersch, Saxe

span.:

batea, chua, challa, prune, zuruca (v.), sarten lavador, batea en forma de bote

Southeast Asia:

dulong, dulang

Manufacturers:

Krantz, Keene

TECHNICAL DATA:

Dimensions:

20 50 cm 0, 5 - 25 cm depth / 15 x 15 x 150 cm HWD / ca 45 - 50 cm diameter, 10 cm depth, 35°- 40° inclination (USA)

Weight:

0,5 - 5 kg

Extent of Mechanization:

not mechanized

Form of Driving Energy:

manual

Mode of Operation:

intermittent

Throughput/Capacity:

cat 1 - 5 kg/mini daily performance 100 pans at 20 Ibs = 1 t/d

Operating Materials:

 

Type:

water

Quantity:

small (can be used in non-flowing water)

ECONOMIC DATA:

Investment Costs:

approx. 10 to 20 DM

Operating Costs:

labor costs only

Related Costs:

none

CONDITIONS OF APPLICATION:

Operating Expenditures:

low |————|————| high

Maintenance Expenditures:

low |————|————| high

Personnel Requirements:

lots of experience is essential for accurate sorting with high recovery

Grain Size of Feed:

< approx. 30 mm

Special Feed Requirements:

free Au as valuable mineral or valuable mineral with very high density

Recovery:

high, also in the fine grain-size range (lower grain-size limit 20 µm), flakes (flour gold) down to 50,um are recoverable in the gold pan

Regional Distribution:

worldwide

Operating Experience:

very good |————|————| bad

Environmental Impact:

low |————|————| very high

Suitability for Local Production:

very good |————|————| bad

Under What Conditions:

simple wood manufacturer or sheet-metal workshop for trays made of galvanized sheet metal

Lifespan:

very long |————|————| very short

Bibliography, Source: Treptow, Schnabel, Agricola, Calvor, Ramdohr, Lepper, Clennell, Silva, Treptow Collection/Freiberg

OPERATING PRINCIPLE:

Through shaking of the pan, gold settles at the deepest point on the pan's bottom. During washing, the tray is moved in such a way that the middle and deepest part, containing the heavy gold particles, remains almost stationary and the lighter tailings, carried along by the flowing water and subject to the radial acceleration forces near the pan's rim, are discharged. This procedure is repeated until only the gold or the black gold-containing sands remain. The final step performed by the gold penner is to slightly tip the pan and lightly knock on the back of the rim in the direction of inclination. This resembles the bumping-table effect whereby the gold accumulates at the highest point of concentrate fan.

AREAS OF APPLICATION:

- for analysis in almost all beneficiation processes

- for sorting of pre-concentrates, for instance, from sluices

- for sorting of gold-containing alluvial deposits

- for semi-quantitative analysis of contents exceeding around 10 g/t

REMARKS:

Gold pans are manufactured from various materials, such as:

- metal

- wood

- half-shell or rind of pumpkin, squash or melon

- PVC

- animal horn (poruna), historically from Argentina and Mexico (bull horn); still being used in arid mining regions in Chile

- rubber (car tires)

The best have proven to be those made of black PVC:

Advantages:

- cracks do not develop

Disadvantage:

- the surface repells water

 

- good gold visibility

   
 

- durable and long-lasting

   
 

- light weight

   

Chromite or ilmenite sands are recommended as contrast medium (added to the raw

material)

Gold tends to undergo flotation. 1 or 2 drops of detergent added to the water, or often also sap from plants (e.f. sisal, spanish: fique) can prevent flotation.

Panning was already described by the Swede Peter Mansson who died in 1536.

The number of individual particles per ounce of gold depends upon the grain size:

small nuggets

10 - 20 mesh:

2200/oz.

big flakes

20 - 40 mesh:

12000/oz. gold

fine flakes

< 40 mesh:

40000/oz.

The minimum particle size visible with the naked eye in a black pan is around 20 ym

The lower limit for manual removal of gold particles is 1 - 2 mm, smaller particles require amalgamation or leaching.

Gold pans are often clearly different in their design depending upon the type of feed to be processed: gold pans used In alluvial deposits are generally significantly flatter (shallower) than those pans used in vein ore mining.

For hand-sorting of fine pre-concentrates, small spray bottles with thin elongated nozzles for sucking up the grain are preferred.

In gold mining in Ecuador, for example, amalgamation is also performed in gold pans. The gold is worked in with a stone for about an hour, after which the mercury, divided into fine beads, is recombined by knocking on the rim of the gold pan. The finest beads, or floured mercury, cannot be refused, due in part to the high surface tension of the mercury or encrustations of fine oxidic mineral dusts, and is carried off and released into the environment during washing of the amalgam. For this reason, this procedure must be considered extremely dangerous and should not be used.

In large-scale facilities, the surface tension of the mercury is relieved by adding cyanide or nitric acid, or less frequently sodium amalgam, caustic soda or ammonium chloride. This is not possible when processing in a gold pan.

SUITABILITY FOR SMALL-SCALE MINING:

Gold pans are used in small-scale mining because of their high degree of separation in all areas of application (prospecting, exploration, analysis during processing, and beneficiation); their use is indispensible. In beneficiation they are primarily employed for cleaning of pre-concentrates. They are characterized by very low throughput quantities and investment costs.


Fig.: Different types of gold pans, above left: "Freiberger" pan, above right: "Salzburger" pan, below left: North American from, below right: Latin American form. Source: Treptow (above) and Schnabel (below).


Fig.: Gold pan designs form the Rhine gold mining region (Germany). Source: Lepper.