Cover Image
close this book Tools for Mining
close this folder Technical Chapter 14: Sorting
View the document 14.1 Jig screen, hand-jigging
View the document 14.2 Simple hand jig, moving bed(percussion) jig
View the document 14.3 Hand piston jig
View the document 14.4 Piston jig, "harzer" jig
View the document 14.5 Pulsator classifier pan american jig
View the document 14.6 Sluices with or without linings/insets, long tom
View the document 14.7 Ground sluice
View the document 14.8 Pinched sluice, fanned sluice
View the document 14.9 Air separator, dry blower
View the document 14.10 Settling basin, buddle
View the document 14.11 Circular buddle
View the document 14.12 Dolly tub
View the document 14.13 Bumping table, concussion table
View the document 14.14 Racking table, tilting frame
View the document 14.15 Sweeping table, belt table
View the document 14.16 Vibrating table
View the document 14.17 Humphrey's spiral, spiral separator
View the document 14.18 Spiral concentrator
Expanding the text here will generate a large amount of data for your browser to display

14.17 Humphrey's spiral, spiral separator

Metal Mining, Gold Mining

Beneficiation, Sorting

germ.:

Humphreyspirale, Wendelscheider, Spiralscheider

span.:

espiral de Humphrey, espiral de separacion por gravedad, separador helicoidal, espiral

TECHNICAL DATA:

Dimensions:

approx. 1 x 1 x 3 m / 5 to 6 windings / 1 to 3 discharge outlets

Weight:

approx. 200 kg

Extent of Mechanization:

not mechanized

Form of Driving Energy:

velocity of slurry/processing water

Mode of Operation:

continuous

Throughput/Capacity:

0.5 12 t/h depending on dimension of channel (launder) and grain size of feed

Operating Materials:

 

Type:

processing water, slurry water

ECONOMIC DATA:

Investment Costs:

approx. 8000 DM

Operating Costs:

low

Related Costs:

possibly slurry pumps

CONDITIONS OF APPLICATION:

Operating Expenditures:

low |————|————| high

Maintenance Expenditures:

low |————|————| high

Location Requirements:

minimum Dh (without pump) of 5 m

Grain Size of Feed:

(50 ym) 100 Ám - 2 mm

Special Feed Requirements:

density difference between valuable mineral and tailings

Recovery:

solids-content of the slurry: 14 - 20 % by vol.

Replaces other Equipment:

other sluice washers

Regional Distribution:

in small-scale mining in Latin America very rare; widely employed in mining in South East Asia (alluvial tin deposits) and Australia

Operating Experience:

very good |————|————| bad

Environmental Impact:

low |————|————| very high

Suitability for Local Production:

very good |————|————| bad

Under What Conditions:

metal foundry

Lifespan:

very long |————|————| very short

 

when lined with wear-resistant rubber

Bibliography, Source: Kirchner, DBM

OPERATING PRINCIPLE:

Spiral separators vertically separate the feed slurry in the launder (channel) according to density differences. The heaviest feed particles fall to the bottom of the launder, where frictional forces slow their velocity. As a result, the slower, heavier grains are less subject to the centrifugal forces (generated by the flow of slurry through the spiral-formed channel) than are the lighter, faster grains higher up in the flow. This creates a horizontal density differentiation of the feed grains, with the heavy particles flowing along the inside walls of the channel, and the faster, lighter particles travelling higher up towards the outer rim. The discharge outlets are located on the inside of the channel for removal of the heavier particles (concentrate). Separation precision can be improved by adding additional water during the sorting process.

AREAS OF APPLICATION:

Production of concentrates or pre-concentrates from medium-grained Feed.

REMARKS:

The launders (channel) are made of rubberized cast-iron or cast-steel or, in more modern constructions, also of fiberglass or ceramic. The design involves numerous pipes for supplementary-water intake and discharge outlets, making the spiral separator a fairly complicated construction.

Critical construction parameters are: launder (channel) cross-section and spiral diameter, number of windings, inclination and number of discharge outlets.

Spirals of this kind were first manufactured by Humphreys in 1943.

SUITABILITY FOR SMALL-SCALE MINING:

The complicated pipe-system for input of auxiliary water and removal of concentrate makes the Humphrey's spiral less suitable for small-scale mining, although as a continual, non-powered sorting apparatus with high throughput it achieves good separation results.


Fig.: Distribution of mineral particles in the Humphreys' spiral. Source: Silva


Fig.: Humphrey's spirals. left, Source: Kirchner, right, Source: Silva.