The OURAY Engineering & Manufacturing, LLC’s (OURAY E & M) Hybrid Mineral Process System is a modular and transportable high yield mineral process unit targeted at producing specific gradations and high value products in the oil and gas proppants industry (frac sand). This system employs technology that is non-typical within the silica sand processing industry as well as proprietary equipment which is historically utilized for mineral handling. Although these units may be relatively non-standard in this application the technology behind the application is well known in other mineral handling/cleaning fields of industry.
Primary Feed Unit:
The primary feed unit consists of grizzly rails suspended above a vibrating screen deck over the top of a hopper unit (very similar to a typical live head grizzly unit). Material is placed onto the grizzly unit and is passed through the bars onto the live head screen by gravity, the grizzly and screens are inclined toward the front or loading side of the unit. The live head screen can have varying sizes of screener mats installed upon which the material is shaken at a relatively high frequency, to make the smaller mineral pass through the screener, at the size allowed, and into the base of the sump. Waste material is discharge due to it being too large to pass through the grizzly or the live head screen.
In the base of the hopper there are several eductor pumps. The quantity of eductor units relies on the amount of desired production for the downstream processes and the amount of detritus contained within the mineral and, therefore; there could be one to nine units installed in a single primary feed unit. If the unit is feed by an overland pipeline or dredge in a slurry format the screener unit is inclined at a steeper angle than a dry feed screen would be.
The eductor pumps installed in the primary sumps are used to transfer the mineral from the primary hopper to the secondary screener unit. The eductor design is a combination of patented and proprietary technologies that have been successfully deployed over several decades of use throughout the mineral handling industry.
The eductor units are used to create a motive water source from a nozzle to move solids in the form of soil, sand or clay into a mixing and diffuser chamber to transport the mineral in a turbulent and constant state to its discharge. The eductor units ensure maximum wetting of the material and high turbulence to enhance separation and subsequent screening/sizing of the mineral being processed.
The eductor units are typically capable of 50 to 90 tons per hour per eductor installed in the sump/hopper.
The secondary screener units receive the transported mineral and water from the Primary Feed Unit. Each secondary unit have a capacity of 150 to 270 tons per hour.
The secondary units have a screener unit consisting of two or three decks supported over a hopper/sump unit. The eductors from the Primary stage discharge onto the top deck of the screener unit and, with the use of vibration and water sprays, the mineral migrates through the smallest deck (typically 1/16 th inch at this stage (size?). The material passing through the smallest screen and into the sump is the material for product processing. The larger material is discharged as either a waste material for disposal or for use as an oversized product.
Like the primary units, the secondary units also have eductors installed into the bottom of the sump. Typically, one to four eductors are utilized to control flow volumes as desired. These eductor units transfer the sized mineral to the tertiary stage.
The “Tangential Shifter” is a vertical or horizontal positioned cylindrical vessel with screening media installed internally. The mineral and water slurry transferred from the secondary screener is received
from the secondary stage at relatively high velocity. The rapidly moving slurry is forced against the inside surface of the internally mounted screening media by tangential forces where the finer mineral sizes can
pass through the media and is discharged to the quaternary stage. The large material that will not pass the through the screen media is discharged to a dewatering and rinsing deck and then subsequently to a
conveyor belt for stockpiling as a product.
The dewatering decks are oversized standard unit to maximize the water recovery from this stage of production and encourage faster drying where required.
The secondary screen represents the mineral product top size and the tertiary stage represents the smaller size.
*This unit is a patent pending proprietary unit specifically designed for managing the accurate cut of a sand/mineral size.
The subsequent stages of the mineral process are basically the same as the Tertiary Stage although the screening media contained within the vessel will be sized differently, usually smaller, except where resizing or reshaping of the mineral is required for mineral enrichment.
- 1. Scrubbing: The typical process (as outlined above) using an eductor unit includes a nominal amount of scrubbing of the particulates passing through the eductor due to the amount of turbulence generated in the mixing chamber however; a high shear attrition scrubber can be included as an option with the process, should the mineral be sufficiently dirty or contaminated with clay or chemicals to require additional cleaning.
The high shear scrubber units are a specifically design eductor with a reactor unit engineered into the mixing chamber. The reactor works by consuming most of the motive power from the input of water and solids and are therefore not useful as a solids transport unit. The scrubber units can be used to also remove or manage chemical, ionic or reduction of contaminants in the form of hydrocarbons or heavy metals that may be associated with the mine or an area spill or leakage into the process from external sources.
- 2. Re-sizing/re-shaping: An enhanced version of the of the scrubbing eductor can be used in themineral process as a stand-alone process step. This unit utilizes a series of angular opposed high velocity attrition scrubber units which essentially utilizes the density of the silica sand to attrite the weaker mineral associated with the mine deposit. The use of this type of process is to increase the crush performance and roundness of the produced sand product. This works by reducing the size of the weaker material which is subsequently washed out with the very fine mineral waste (super fines & clays) associated with the mined material. T
his method can be enhanced with the inclusion of engineered scrubbing media for the higher density minerals.
Note; If these processes are used the mineral properties are increased however; the mineral yield may be decreased due to the waste material being removed from the mineral gradation.
Water Handling / Recycling:
The wet plant process includes a basic system to recycle water back into the motive pumps from a water reserve or mud-pond based system. The water recycling units are semi-mobile high capacity coalescing units that will remove solids and floatable from the water flow to meet the demands of the process plant. These units do not replace the need for water treatment, however they do reduce the need for high chemical loads typically used in other systems.
The provision of a water treatment system would also include eductor based enhancements to ensure the treated water is free from unwanted elements that may impact on the quality of the output product
associated with the process plant. The water treatment system would be designed around the engineering data provided for the mine and the mineral for processing.
A complete water system can include, fixed or mobile clarifiers, chemical dosing for precipitation (floatable or sinkable), cationic or ionic metals removal, sand filters and any other applicable water technology required to maintain an economically stable and efficient water treatment unit.