Patent Description:
A variety of different crushers have evolved for processing bulk material such as stone, minerals and both domestic and industrial waste including construction materials to generate a crushed product for subsequent processing or disposal. Known crushers include cone, impact, vibration and jaw crushers. Crushers can also be categorised into mobile crushers that are readily transportable from one site to another and stationary crushers designed for large static installations that are assembled on site e.g. at a quarry or mine environment where they remain until the source of raw material is exhausted.

Mobile crushers typically have endless tracks or wheels mounted at the undercarriage of a main chassis of the mobile crusher.

Generally, crushers are provided with a feed station for receiving crusher feed bulk material from a hopper and feeding the bulk material to the crusher. Known feed stations are made up of a feeder such as a vibrating pan feeder for receiving bulk material from a hopper and can include screening apparatus to remove undersize material such as natural fines from the bulk material prior to crushing to prevent blockages in the crusher and improve crusher performance. The removed material can then be combined with the crushed product and/or treated as a useful commercial byproduct of the crushing process e.g. the natural fines.

However, known feed stations can be inefficient at removing undersize material from bulk material and are unable to generate more than one byproduct from the undersize material.

From <CIT> there is known a crushing plant having elevator means located primary and secondary crushers, each comprising first and second stage crushing devices. The crushing plant comprising a grizzly and a vibratory screen device having three superimposed screens that are vibrated in a fore and aft direction by an eccentric mechanism to cause carryover material of greater than finish size which fails to pass through the screens, to be vibrationally advanced in the forward direction towards the primary crusher.

From <CIT> there is known a method for operating an aggregate material processing plant according to two alternative modes of operation. In a first operating mode, unprocessed aggregate material is deposited onto a crusher feed conveyor and then fed to a crusher. The crusher produces crushed aggregate material, which is conveyed by a collection conveyor to a vibratory screen assembly at a first speed. The vibratory screen assembly sizes aggregate material deposited onto an upper screen deck thereof. Unscreened aggregate material is conveyed by a transfer conveyor to the crusher feed conveyor. In a second operating mode, unprocessed aggregate material is deposited onto the vibratory screen assembly, which sizes the aggregate material. The transfer conveyor conveys unscreened aggregate material to the crusher feed conveyor. The crusher feed conveyor feeds aggregate material to the crusher, which produces crushed aggregate material. The collection conveyor conveys crushed aggregate material to the vibratory screen assembly at a second speed.

From <CIT> there is known a method of continuously recovering classified aggregates of different sizes in a recirculating conveyor system including, first and second crushers, which consists in, passing pit run material over a first screen to separate said pit run material into a relatively fine material and a coarse material, feeding said coarse material direct to the first crusher, screening the throughs from the first screen to divide out a quickly recoverable product and an intermediate product too coarse for said quickly recoverable product but so fine as to impair the efficiency of the first crusher and requiring further processing, by-passing the intermediate product around the first crusher, and returning said intermediate product into the recirculating system for subsequent reduction by the second crusher and further screening.

An object of the invention is to provide a crusher feed station adapted to efficiently remove undersize material from a crusher feed bulk material and generate more than one byproduct from the bulk material.

In one aspect of the invention there is provided a crusher feed station for feeding feed material to a crusher configured to produce a sized crushed product, the crusher feed station comprising:.

In one embodiment, a first upper deck of the three screening decks comprises a first deck screening media sized to produce the first sizing screen oversize product. The first sizing screen oversize product is therefore sized as required in accordance with production requirements.

Preferably, the first deck screening media is sized to size the first sizing screen oversize product in accordance with the sized crushed product. The first sizing screen oversize product can therefore be combined with the sized crushed product without being crushed.

In one embodiment, the first upper deck and a second and third lower deck of the three screening decks comprise screening media sized to produce the second fines product as a throughput product. The second fines product does not therefore enter the crusher and can be treated as a graded finished product.

Suitably, the second and third lower decks comprise screening media sized to produce the third intermediate sized product as a second and third lower deck oversize product. This oversize product therefore results in an additional saleable product.

In any embodiment, the crusher feed station further comprises a third intermediate sized product conveyor for conveying the third intermediate product from the crusher feed station. The third intermediate sized product conveyor can remove the third intermediate sized product from the crusher feed station for bagging and the like.

In any embodiment, the crusher feed station further comprises a fines product conveyor for conveying the fines product from the crusher feed station. The fines product conveyor removes the fines product from the crusher feed station for bagging etc..

In any embodiment, the sizing screen comprises a vibrating sizing screen. The vibrating screen effectively screens the undersize (underflow) fraction.

In any embodiment, the primary feeder comprises a vibrating pan feeder. The vibrating pan feeder effectively feeds the feed material to the scalping deck.

In another embodiment, the invention also extends to a crusher comprising a crusher feed station as hereinbefore defined. A crusher incorporating the crusher feed station exhibits optimal efficiency as a high percentage of undersize material is removed before crushing and a clean, saleable third intermediate product in addition to the second fines product is produced.

In one embodiment, the crusher further comprises a discharge conveyor for conveying sized crushed product from the crusher and the discharge conveyor is located beneath a discharge end of the sizing screen to receive first sizing screen oversize product from the sizing screen. The discharge conveyor therefore conveys both sized crushed product and first sizing screen oversize product from the crusher.

In any embodiment, the crusher comprises a jaw crusher, a cone crusher or an impact crusher.

In a second aspect of the invention there is provided a method of feeding feed material from a feeding station to a crusher configured to produce a sized crushed product from the feed material, the method comprising:.

In one embodiment, the undersize (underflow) fraction is screened by a first upper deck of the three screening decks to produce the first sizing screen oversize product. The first sizing screen oversize product is therefore sized as required in accordance with production requirements.

In one embodiment, the undersize (underflow) fraction is screened by the first upper deck and a second and third lower deck of the three screening decks to produce the second fines product as a throughput product and by the second and third lower decks to produce the third intermediate product as a second and third lower deck oversize product. The method therefore results in the production of two finished or saleable products at the material feed stage of the production process.

<FIG> and <FIG> show a mobile crusher <NUM> provided with a crusher feed station <NUM> of the invention in which the mobile crusher <NUM> is generally made up of a mainframe <NUM> on a chassis <NUM> provided with wheels <NUM> and a jaw crusher <NUM> mounted on the mainframe <NUM> for crushing bulk material to form a crushed main product which is conveyed from the mobile crusher <NUM> on a main product discharge conveyor <NUM> disposed beneath the jaw crusher <NUM>. As shall be explained more fully below, the crusher feed station <NUM>, which can be mounted on the mainframe <NUM> to receive bulk material from a feed hopper <NUM> and a primary feeder <NUM> also mounted on the mainframe <NUM>, has a scalping deck <NUM> and a sizing screen <NUM> configured to produce a first sizing screen oversize product, a second fines product and a third intermediate sized product.

<FIG> shows an enlarged perspective view from above and one side of the crusher feed station <NUM> and associated feed hopper <NUM> and primary feeder <NUM> separated from the mobile crusher <NUM>. As shown in the drawing, the primary feeder <NUM> is disposed in feed hopper <NUM> and extends from the feed hopper <NUM> towards the scalping deck <NUM> which is positioned above the sizing screen <NUM>. The scalping deck <NUM> terminates at a scalping deck discharge end <NUM> from which a scalping deck oversize feed is fed from the scalping deck <NUM> into the jaw crusher <NUM> (see also <FIG> and <FIG>) for crushing.

The sizing screen <NUM> is disposed beneath the scalping deck <NUM> for screening the undersize (underflow) fraction from the scalping deck <NUM> and has a sizing screen discharge end <NUM> for discharging screened material from the sizing screen <NUM>. The sizing screen <NUM> is a triple deck sizing screen <NUM> having a first upper screening deck <NUM> disposed immediately beneath the scalping deck <NUM>, a second or middle screening deck <NUM> disposed beneath the upper screening deck <NUM> and a third or lower screening deck <NUM> disposed beneath the second screening deck <NUM>.

In order to produce the first sizing screen oversize product, the second fines product and the third intermediate sized product, the upper screening deck <NUM> is provided with an upper deck screening media <NUM>, the second screening deck <NUM> is provided with a second deck screening media <NUM> and the third screening <NUM> deck is provided with a third deck screening media <NUM>. The first deck screening media <NUM> is sized to produce the first sizing screen oversize product e.g. in accordance with the sized crushed product. The first upper screening deck <NUM>, the second screening deck <NUM> and the third lower screening deck <NUM> have respective screening media <NUM>,<NUM>,<NUM> sized to produce the second fines product as a throughput product. The screening media <NUM> of the second screening deck <NUM> and the screening media <NUM> of the third lower screening deck <NUM> are also sized to produce the third intermediate sized product as a second screening deck <NUM> and third lower screening deck <NUM> oversize product.

The crusher feed station <NUM> is further provided with a third intermediate sized product conveyor <NUM> disposed beneath the sizing screen discharge end <NUM> of the second screening deck <NUM> and the third lower screening deck <NUM> to convey the third intermediate product from the crusher feed station <NUM>. The longitudinal axis of the third intermediate sized product conveyor <NUM> is disposed substantially perpendicular to the longitudinal axis of the sizing screen <NUM> and a chute <NUM> is positioned above the third intermediate product conveyor <NUM> to guide the third intermediate product onto the third intermediate product conveyor <NUM>. In addition, the crusher feed station <NUM> is also provided with a fines product conveyor <NUM> adjacent the third intermediate sized product conveyor <NUM> and disposed beneath the third lower screening deck <NUM> for conveying the fines product from the crusher feed station <NUM> and a chute <NUM> is also positioned above the fines product conveyor <NUM> to guide the fines product onto the fines product conveyor <NUM>. The longitudinal axis of the fines product conveyor <NUM> is also disposed substantially perpendicular to the longitudinal axis of the sizing screen <NUM>.

As shown in the drawing, the discharge conveyor <NUM> for conveying sized crushed product from the jaw crusher <NUM> (see also <FIG> and <FIG>) is also located beneath the discharge end <NUM> of the sizing screen <NUM> to receive the first sizing screen oversize product from the sizing screen <NUM> so that the first sizing screen oversize product is combined with the sized crushed product.

The operation of the crusher feed station <NUM> will now be described having regard to <FIG> and <FIG> in which the direction of movement of bulk material through the feed station <NUM> is indicated by the arrows in <FIG> and the three screening decks <NUM>,<NUM>,<NUM> of the sizing screen <NUM> are more clearly illustrated in <FIG>.

As shown in the drawings, feed material from the hopper <NUM> is conveyed by the primary feeder <NUM>, which is typically a vibrating pan feeder <NUM>, to the scalping deck <NUM>. The scalping deck <NUM> removes undersize materials from the feed material to form a scalping deck oversize crusher feed and an undersize (underflow) fraction and the scalping deck oversize crusher feed is fed to the jaw crusher <NUM> (see <FIG> and <FIG>) for crushing and removal as a sized crushed product by the main product discharge conveyor <NUM> (see also <FIG>) and the undersize (underflow) fraction descends to the triple deck sizing screen <NUM> for further processing.

At the triple deck sizing screen <NUM>, the screening media <NUM> of the first upper deck <NUM> screens the material to produce the first sizing screen oversize product. Typically, the first deck screening media <NUM> is sized to size the first sizing screen oversize product in accordance with the sized crushed product which descends from the discharge end <NUM> of the sizing screen <NUM> onto the main product discharge conveyor <NUM>.

The screening media <NUM>,<NUM>,<NUM> of the first upper screening deck <NUM>, the second screening deck <NUM> and the third screening deck <NUM> are sized so that throughput product that passes through the three screening decks <NUM>,<NUM>,<NUM> forms the second fines product which is conveyed from the feed station <NUM> by the fines product conveyor <NUM> as finished processed product.

In addition, the respective screening media <NUM>,<NUM> of the second and third lower decks <NUM>,<NUM> are sized to produce the third intermediate sized product as a second and third lower deck <NUM>,<NUM> oversize product which descends from the discharge end <NUM> of the sizing screen <NUM> onto the third intermediate product conveyor <NUM> which conveys the third intermediate product from the feed station <NUM> as an additional finished processed product.

Claim 1:
A crusher feed station (<NUM>) for feeding feed material to a crusher (<NUM>) configured to produce a sized crushed product, the crusher feed station (<NUM>) comprising:
a primary feeder (<NUM>);
a scalping deck (<NUM>) for removing undersize materials from the feed material to form a scalping deck oversize crusher feed and an undersize (underflow) fraction and
a sizing screen (<NUM>) beneath the scalping deck (<NUM>) for screening the undersize (underflow) fraction wherein the sizing screen (<NUM>) comprises at least three screening decks (<NUM>,<NUM>,<NUM>), characterized in that the sizing screen (<NUM>) is configured to produce a first sizing screen oversize product, a second fines product and a third intermediate sized product.