Method of use of aggregate processing equipment

Abstract

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.

Claims

1. A method for operating an aggregate material processing plant according to first and second alternative modes of operation, said method comprising the steps of: (a) providing an aggregate material processing plant comprising: (i) a crusher; (ii) a crusher feed conveyor that is adapted to feed aggregate material to the crusher; (iii) a vibratory screen assembly comprising an upper screen deck; (iv) a collection conveyor that is adapted to collect aggregate material that has passed through the crusher and to convey such crushed aggregate material to the vibratory screen assembly at a first speed or at a second speed which is slower than the first speed; (v) an upper transverse conveyor that is adapted to collect aggregate material that is too large to pass through the upper screen deck and to convey such un-screened aggregate material away from the vibratory screen assembly; (vi) a transfer conveyor that is adapted to collect un-screened aggregate material that has been conveyed away from the vibratory screen assembly by the upper transverse conveyor and to convey such un-screened aggregate material to the crusher feed conveyor; (b) wherein the first mode of operation of the method comprises: (i) depositing unprocessed aggregate material onto the crusher feed conveyor; (ii) operating the crusher feed conveyor to feed aggregate material to the crusher; (iii) operating the crusher to produce crushed aggregate material; (iv) operating the collection conveyor to convey crushed aggregate material to the vibratory screen assembly at the first speed; (v) operating the vibratory screen assembly to size aggregate material that has been deposited onto the upper screen deck; (vi) operating the transfer conveyor to convey unscreened aggregate material to the crusher feed conveyor; (c) wherein the second mode of operation of the method comprises: (i) depositing unprocessed aggregate material onto the vibratory screen assembly; (ii) operating the vibratory screen assembly to size aggregate material that has been deposited onto the upper screen deck; (iii) operating the transfer conveyor to convey unscreened aggregate material to the crusher feed conveyor; (iv) operating the crusher feed conveyor to feed aggregate material to the crusher; (v) operating the crusher to produce crushed aggregate material; (vi) operating the collection conveyor to convey crushed aggregate material to the vibratory screen assembly at the second speed.

2. The method of claim 1 wherein the second mode of operation comprises simultaneously depositing unprocessed aggregate material onto the vibratory screen assembly and onto the crusher feed conveyor.

3. The method of claim 2 wherein the second mode of operation comprises depositing unprocessed aggregate material onto a first portion of the vibratory screen assembly; and operating the collection conveyor to convey crushed aggregate material to a second portion of the vibratory screen assembly.

4. The method of claim 2 wherein the unprocessed aggregate material onto the vibratory screen assembly is smaller in size than the unprocessed aggregate material deposited onto the crusher feed conveyor.

5. The method of claim 1 further comprising the steps of: providing a mobile aggregate material processing plant; and moving the mobile aggregate material processing plant to an aggregate material processing location.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The presently preferred embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:

(2) FIG. 1 is a top perspective view of a conventional portable aggregate processing plant that may be operated according to the method of the invention.

(3) FIG. 2 is a top view of the portable processing plant shown in FIG. 1.

(4) FIG. 3 is a side view of the portable processing plant shown in FIGS. 1 and 2.

(5) FIG. 4 is a side schematic view of a conventional portable aggregate processing plant such as is illustrated in FIGS. 1-3, showing a first mode of operation according to the method of the invention.

(6) FIG. 5 is a side schematic view of a conventional portable aggregate processing plant such as is illustrated in FIGS. 1-3, showing a second mode of operation according to the method of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(7) This description of the preferred embodiments of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawings are not necessarily to scale, and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness.

(8) As shown in the drawings, conventional portable processing plant 10 comprises frame 12 which is supported by left and right track drive assemblies, one of which, left track drive assembly 14 is shown in FIGS. 1 and 3. The track drive assemblies are steerable and are typically operated by hydraulic or electric motors. In the alternative, wheeled drive assemblies may be provided comprising left and right front and rear wheel drive assemblies, at least some of which are steerable. Power for operation of the motors that are employed to operate the drive assemblies is usually provided by a diesel engine (not shown), or by local electric power.

(9) A crusher, such as cone crusher 16, is mounted on frame 12 above the drive assemblies. Crusher feed conveyor 18 and feed chute 20 are provided to feed material to be processed into the top of crusher 16. Cone crusher 16 operates to reduce the size of aggregate material introduced through feed conveyor 18 and includes a conventional housing that contains in its upper section a moveable cone (not shown) and a concave or bowl liner (also not shown). The cone is mounted on a crusher shaft (also not shown), and the concave or bowl liner is fixed to the upper part of the crusher housing. Aggregate material to be crushed is fed via feed chute 20 to crusher feed conveyor 18, which drops it into the gap between the cone and the concave or bowl liner of cone crusher 16. This gap is adjustable in width in order to control the top size of material passing through the crusher. The crushing force is produced by an eccentric component, which drives the crushing cone towards the crushing concave or bowl liner in a circular oscillating movement. Due to the friction of the material to be crushed against the cone and concave or bowl liner, the crushing cone moves slowly around the concave in the direction opposite to that of the driving rotation.

(10) Aggregate material that passes through crusher 16 falls onto crusher collection conveyor 22 that delivers crushed material to vibratory screen assembly 24. Vibratory screen assembly 24 is comprised of upper screen deck 26 and lower screen deck 28 (shown in FIGS. 4 and 5) which are mounted in an inclined configuration. In other embodiments of the invention, only one, or any suitable number of screen decks may be provided. Each screen deck generally comprises sizing media such as woven wire cloth or perforated plates. The sizing media has openings that dictate the largest sized aggregate particle that can pass through the media, and in a screen assembly with multiple screen decks, each screen deck has larger sizing openings than the screen deck located immediately below. An impulse mechanism (not shown) is provided to generate vibrational motion and to impart such motion to the screen decks of screen assembly 24. This vibration is designed to stratify the aggregate material as it flows across the screen decks and to expose the aggregate material particles to the media openings. Aggregate material to be classified by particle size flows across the length of each screen deck and across the sizing media as the impulse mechanism vibrates the screen deck. The vibrations imparted to the screen deck cause material small enough to pass through the openings in the sizing media to pass through to a lower screen deck or transfer conveyor. It also helps to convey the aggregate material across the screen deck and prevents material build-up on the sizing media. Thus, as shown in FIGS. 4 and 5, aggregate material that is retained on upper screen deck 26 (i.e., aggregate material that is too large to pass through the upper screen deck) is carried down to the lower end of deck 26 and off the upper screen deck onto upper transverse conveyor 30, which carries the aggregate material to transfer conveyor 32 which conveys it to feed chute 20. Aggregate material that passes through upper screen deck 26 but is retained on lower screen deck 28 is carried down to the lower end of deck 28 and off the lower screen deck onto transverse discharge conveyor 34, which carries the aggregate material away from machine 10 to a stockpile (not shown). In the alternative, transverse discharge conveyor 34 may be reversed to carry the material to transfer conveyor 32 which conveys it to feed chute 20. Aggregate material that passes through both upper screen deck 26 and lower screen deck 28 falls onto longitudinal discharge conveyor 36 for transport to stockpile 38.

(11) The invention comprises a method of operation of aggregate processing plant 10 according to two alternative modes of operation. According to the invention, the operating speed of crusher collection conveyor 22 is varied, between a first speed and a second speed which is less than the first speed, to control the rate of placement of the crushed material onto vibratory screen assembly 24. When loading aggregate material only into crusher feed conveyor 18, as shown in FIG. 4, crusher collection conveyor 22 is operated at the first speed to discharge the crushed aggregate material near the upper end of screen assembly 24 to get maximum efficiency. When loading unprocessed aggregate material onto vibratory screen assembly 24 instead of crusher feed conveyor 18, as shown in FIG. 5, crusher collection conveyor 22 is operated at the second speed to discharge crushed aggregate material lower on the vibratory screen assembly to relieve the load on and improve the performance of the screen assembly.

(12) The invention thus provides a method of operation of an aggregate processing plant according to two alternative modes of operation, which does not require processing all of the aggregate material through the crusher of the processing plant or the addition of a pre-screen component.

(13) Although this description contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventor of carrying out the invention. The invention, as described and claimed herein, is susceptible to various modifications and adaptations as would be appreciated by those having ordinary skill in the art to which the invention relates.