WO2001064347A2

WO2001064347A2 - Spiral concentrator unit

Info

Publication number: WO2001064347A2
Application number: PCT/ZA2001/000027
Authority: WO
Inventors: Marcel Albert Rocher
Original assignee: Multotec Process Equipment Pty Ltd
Current assignee: Multotec Process Equipment Pty Ltd
Priority date: 2000-03-02
Filing date: 2001-03-02
Publication date: 2001-09-07
Anticipated expiration: 2002-09-02
Also published as: WO2001064347A3; AU4600601A

Abstract

According to a first aspect of the invention, there is provided a process for manufacturing a spiral concentrator unit including the steps of providing a first mould (10) for moulding an inner, slurry bearing polyurethane layer; providing a fibreglass backing layer (13), located so as to create an enclosed cavity (12) between the first mould and the backing layer; and filling the mould cavity (12) with polyurethane, allowing the polyurethane to cure and bond with the backing layer (13) so as to produce a spiral trough with a uniform, high wear resistant inner layer of polyrethane and a relatively cheaper fibreglass backing layer.

Description

SPIRAL CONCENTRATOR UNIT

Technical Field

This invention relates to a spiral concentrator unit. More particularly but

not exclusively, the invention relates to a spiral concentrator unit and a

method for making such unit.

Background Art

The use of concentrators such as spirals for the separation of minerals such

as heavy minerals, for example gold, is well known. These spirals were

originally made of wood, but are now primarily made of glass fibre and

plastics material More recently, the high wear zones, that is, the zones

where the surfaces of the spiral come into contact with slurry, such as the

inner surface of the spiral trough, the feed box and the product box are

being covered or made of high wear resistant materials such as

polyurethane.

The disadvantage of using high wear resistant materials such as

polyurethane is however, its relatively higher cost to that of the more

common plastics materials such as polyethylene. The feed and the product boxes are conventionally made separately and

then retrofitted, taking into account operational characteristics such as the

required product split, e.g. whether and where the slurry should be

separated into a concentrate, a middlings and/ or a tailings. A disadvantage

of spirals in which the feed and/or product boxes are not integral with the

spiral is the need to retrofit the boxes and the additional polyurethane

required in the high wear zones created because of it.

Spirals are conventionally manufactured manually, typically by applying a

releasing agent to a spiral working mould and subsequently spraying the

mould with a layer of polyurethane to a required thickness. After the

polyurethane has cured, the polyurethane layer is supported with a backing

layer of fibreglass matt and resm which, when cured, is de-moulded The

feed and product boxes are then retrofitted. A disadvantage of the present

manufacturing process is the high rejection ratio of the final products, due

to surface imperfections caused either during the spraying of the

polyurethane layer or during the application of the fibreglass backing. A

further disadvantage of the method of manufacture is that it is time

consuming and labour intensive. An additional disadvantage of the present method of manufacture is the

inability to produce a final product m which the spiral is integral with the

feed and/or product boxes, leading to the associated disadvantage of more

expensive products due to the additional polyurethane as set out above.

Another disadvantage of the present method of manufacture is its relative

inability to control aspects such as the layer thickness of the relatively

expensive polyurethane, the temperature of the polyurethane during

application and curing, the need to use the more expensive spraying

polyurethane than the cheaper castable polyurethane and the rate of

application.

It is accordingly an object of this invention to minimize the above

disadvantages or at least to provide an alternative spiral design and method

of manufacture.

Disclosure of the Invention

A counter mould may be provided, defining an outer shape of the backing

layer.

The process may include the steps of locating a fibreglass backing layer

within the counter mould in a partially cured, pre-impregnated state; and introducing the polyurethane into the cavity between the first mould and

the backing layer, allowing the polyurethane to cure substantially

simultaneously with the fibreglass.

Alternatively, the process may include the steps of providing a second

mould, moulding the fibreglass backing layer in an enclosed mould cavity

between the counter mould and the second mould; substituting the second

mould with the first mould, the latter located proximate to the backing

layer so as to create an enclosed mould cavity between the backing layer

and the first mould,; and filling the mould cavity with polyurethane.

The spiral trough may be integrally moulded with a feed and/or a product

box, the feed and/or product box preferably being made of polyurethane.

Alternatively, the spiral trough may be retrofitted with a feed and/or a

product box, the boxes preferably being made of polyethylene or other

suitable material.

The first mould may be dimensioned and configured to create a

polyurethane mould cavity which provides for a predetermined

polyurethane layer thickness as well as specific polyurethane location while

limiting an oversupply of polyurethane, thus producing the most desirable

but cost effective polyurethane layer. According to a second aspect of the invention there is provided a spiral

concentrator unit manufactured by a process substantially as hereinbefore

defined.

According to a third aspect of the invention there is provided a spiral

concentrator unit being manufactured by a process substantially as

hereinbefore defined, the spiral concentrator unit including a spiral trough,

a feed box and/or a product box, the spiral concentrator being

characterised in that the spiral trough is integrally moulded with the feed

and/or the product box.

Brief Description of the Drawings

A preferred embodiment of the invention will now be described by means

of a non-limit g example only and with reference to the accompanying

drawings wherein :

Figure 1 is a side view of a spiral concentrator unit in accordance with

the invention; and

Figure 2 is a cross-sectional side view of a polyurethane punch and

counter mould arrangement. Please note that the same reference numerals are used to denote

corresponding parts in the accompanying drawings.

Best Mode of Carrying Out the Invention

A spiral concentrator unit (1) in accordance with the invention and as

illustrated in figure 1 includes a centre column (2), a spiral trough (3), a

feed box (4) and a product box (5).

The feed box (4) and the product box (5) are integrally moulded with the

spiral trough (3).

The spiral trough (3) includes an inner, high wear resistant layer (3.1) of

polyurethane, supported by a relatively cheaper fibreglass backing (3.2).

It is envisaged that the feed box (4) and the product box (5) could be

retrofitted to the spiral trough (3) and that such feed box and/or product

box could be made of polyurethane, alternatively, polyethylene or any

other suitable material or combination of materials.

The spiral (1) is manufactured in an enclosed moulding process as

illustrated in Figure 2, the process including the steps of providing a first

mould or so-called polyurethane transfer mould (10); providing a counter mould (11), so as to create an enclosed mould cavity (12) between the first

mould and the counter mould; locating suitable pre-impregnated matt (13)

in the mould cavity; and filling the mould cavity with polyurethane (not

shown), thus allowing the polyurethane to cure to produce a moulded

layered spiral trough with a uniform, high wear resistant inner layer of

polyurethane (3.1) and a relatively cheaper fibreglass support (3.2), the

layers being integrally moulded with the minimum of surface imperfections

on the external surface of the polyurethane inner layer.

Alternatively, the spiral (1) may be manufactured in an enclosed moulding

process as illustrated partially m figures (3) and (4), the process including

the steps of providing a second or so-called resm transfer mould (14);

providing a counter mould (11), for the resm transfer mould so as to create

an enclosed resm mould cavity (13) therebetween; locating suitable

fibreglass matt in the mould cavity; filkng the mould cavity with resm (not

shown) and allowing the resm to cure so as to produce a fibre glass backing

(3.2), substituting the resm transfer mould with a first, polyurethane

transfer mould (10), using the fibre glass backing (3.2) to create an

enclosure polyurethane mould cavity (23) therebetween; and filling the

mould cavity with polyurethane (not shown) and allowing the polyurethane

to cure to produce a moulded layered spiral trough with a uniform, high wear resistant inner layer of polyurethane (3.1) and a relatively cheaper

fibre glass support (3.2), the layers being integrally moulded with the

minimum of surface imperfections on the polyurethane inner surface.

The spiral concentrator unit (1) is integrally moulded with the feed box (4)

and the product box (5), the feed box and the product box being made of

polyurethane.

Alternatively, it is envisaged that the spiral concentrator unit (1) could be

retrofitted to a feed box (4) and a product box (5), the boxes being made

of polyurethane, polyethylene or any other suitable material.

The first mould (10) is dimensioned and configured to create the mould

cavity (12) and (23) which provides for a polyurethane layer thickness,

cured at a predetermined temperature, as well as polyurethane location

while limiting polyurethane oversupply so as to produce the most durable

but cost-effective polyurethane layer (3.1).

It will be appreciated that many variations in detail are possible without

departing from the scope and or spirit of the invention as claimed below,

such as controlling the polyurethane and/or resm temperature, the

polyurethane and/or resm input, etc.

Claims

1. A process for manufacturing a spiral concentrator unit characterised

by including the steps of :

providing a first mould for moulding an inner, slurry bearing

polyurethane layer:

providing a fibreglass backing layer, located and arranged so

as to create an enclosed mould cavity between the first mould

and the backing layer; and

filling the mould cavity⁷ with polyurethane, allowing the

polyurethane to cure and bond with the fibreglass backing

layer so as to produce a multi- layered spiral trough with a

uniform, high wear resistant inner layer of polyurethane and a

relatively cheaper fibreglass backing layer.

2. A process for manufacturing a spiral concentrator unit as claimed in

claim 1, characterised by including the steps of providing a counter

mould defining an outer shape of the backing layer; locating the fibreglass backing layer in a partially cured, pre-impregnated state

between the first mould and the counter mould; introducing the

polyurethane into the cavity between the first mould and the

backing layer; and allowing the polyurethane to form the high wear

resistant inner layer while curing simultaneously with the fibreglass.

A process for manufacturing a spiral concentrator unit as claimed m

claim 1, characterised by including the steps of providing a second

mould, for moulding the fibreglass backing layer in an enclosed

mould cavity between the second mould and a counter mould;

filling the mould cavity with fibreglass and resm, allowing the resm

to cure; removing the second mould; locating the first mould

proximate to the counter mould with the backing layer retained

therein, so as to create an enclosed mould cavity between the

backing layer and the first mould; and filling the mould cavity with

polyurethane so as to produce the multi-layered spiral trough.

4. A process for manufacturing a spiral concentrator unit as claimed in

claim 1, 2 or 3, characterised by including the step of integrally

moulding the spiral concentrator unit with at least one of a feed and

a product box.

5. A process for manufacturing a spiral concentrator unit as claimed in

claim 4, characterised by manufacturing at least one of the feed and

the product boxes of polyurethane.

6 A process for manufacturing a spiral concentrator unit as claimed in

claim 1, characterised by including the step of retro fitt g the spiral

concentrator unit with at least one of a feed and a product box.

7. A process for manufacturing a spiral concentrator unit as claimed in

claim 6, characterised by manufacturing the spiral concentrator with

at least one of the feed and product boxes of polyurethane.

8. A process for manufacturing a spiral concentrator unit as claimed m

claim 1, characterised by dimensioning and configuring the first

mould to create a polyurethane mould cavity which provides for a

predetermined polyurethane layer thickness as well as specific

polyurethane location while limiting an oversupply of polyurethane,

thus producing the most desirable but cost effective polyurethane

layer.

A spiral concentrator unit characterised by being manufactured by a

process including the steps of:

providing a first mould for moulding an inner, slurry bearing

polyurethane layer;

providing a fibreglass backing layer, located and arranged so

as to create an enclosed mould cavity between the first mould

and the backing layer; and

- filling the mould cavity with polyurethane, allowing the

polyurethane to cure and bond with the fibreglass backing

layer so as to produce a multi-layered spiral trough with a

uniform, high wear resistant inner layer of polyurethane and

a relatively cheaper fibreglass backing layer.

10. A spiral concentrator unit having a spiral trough, a feed box and a

product box, the spiral concentrator being characterised in that the

spiral trough is integrally moulded with at least one of the feed and

the product boxes.

1. A spiral concentrator unit as claimed n claim 10 characterised in

having an integrally moulded multi-layered spiral trough with a

uniform high wear resistant inner, slurry bearing layer of

polyurethane and a relatively cheaper fibreglass backing layer.