Technical Report for the Sandtown Frac Sand Property — 2015

The 2015 technical report describes an entirely mechanical processing route for the Sandtown Frac Sand Property, targeting the production of three proppant sand gradations and a fine silica product through crushing, wet classification, and water recovery circuits.

The Sandtown Frac Sand Property processing plant is designed to convert sandstone into three specific frac sand gradations plus a fine silica size fraction. The proposed process is entirely mechanical, requiring no chemical treatments, additions, or nonstandard material handling processes. The primary objective is liberation and size classification rather than chemical extraction. For proppant sand, no specific size reduction or grain manufacture is required, as the sand grains within the rock type are of optimal size and shape. To manufacture the fine grain sand, a grinding circuit would be considered to achieve the 200/400 mesh range.

Testwork completed to date, used for developing process design criteria, indicates a recovery of proppant sand from the product stream of 70 percent, a value recognized as conservative with improvement expected from further testwork. Notably, aside from proppant test work to determine overall quality, no prototype metallurgical work has been conducted specifically oriented towards extraction, separation, marketing, and production of the silica sand.

Critical Data

Overview

Select Sands Corp has developed process design criteria for the Sandtown Frac Sand Project using information from its related experience and knowledge, metallurgical test data from STIM-Lab, and sample tests from Tetra Tech. The plant design aims to recover and ship approximately 882,000 st/y of sand. The processing facility integrates both dry and wet processing components. RoM material would be transported via mine haul trucks to a stockpile location, from where a front end loader (FEL) would reclaim material to feed into the crushing plant. The crushing plant is designed as a portable unit to provide flexibility between mine and process operations.

The process design includes several distinct stages. The crushing circuit reduces sandstone to manageable sizes without damaging individual grains. Subsequent wet processing further liberates silica particles, removes non-silica contaminants and clay impurities, and segregates non-frac sand size fractions. The wet plant includes a primary scalping screen, attrition scrubbing station, a series of single stage frac sand plants, and a fine grinding and recovery station. All minus 400 mesh material is collected in a thickener/clarifier, with the thickened slurry pumped to a plate and frame filter press to maximize water recovery for recycling back to the plant.

Key Process Stages

The process plant involves both dry and wet processing components. Run-of-mine material is stockpiled near the process feed facilities, reclaimed via front end loader into a portable crushing circuit. The crushing plant considered includes a vibrating grizzly feeder, a horizontal impact crusher, loading hopper, under crusher discharge conveyor, cross belt magnet, single deck inclined screen, and transfer conveyors.

Subsequent to crushing, the wet plant process further liberates silica particles, removes contaminants and impurities, and classifies the sand into predetermined size classifications. Material from the transfer conveyors is received onto a vibrating double deck scalping screen. The underflow flows to a dewatering screen for dewatering. The underflow of the hydrosizer (30 x 40-50 mesh material) flows to a dewatering screen, as does the underflow of the hydrosizer (50 x 70 mesh material). The tertiary hydrosizer overflow flows to the final stage, an ultra-sand plant. The overflow of this plant, which is minus 400 mesh material, flows to a thickener/clarifier system.

The wet plant consists of a primary scalping screen, attrition scrubbing station, a series of single stage frac sand plants, and a fine grinding and recovery station. Wet products from each separation station are stored in a concrete bunker area for reclamation by a front end loader. The material is transported to a fluidised heat bed dryer. From the dryer, bucket elevators carry the feed material into a surge hopper that loads onto weigh-belt feeders feeding screeners, which in turn transport the dried product to associated product storage silos.

The water recovery circuit uses a thickener and a recessed plate filter press. The thickener collects all minus 400 mesh material, while the thickened slurry is pumped to the filter press to maximize water recovery, which is then recycled back to the plant.

Additional Interesting Data and Summary

The processing plant design includes a fine product grinding circuit featuring a ceramic lined ball mill, 16.4’ x 20.5’, with 2000 HP, along with a hydrocyclone pack and dewatering screen. The product drying and storage area includes a vibrating fluid bed dryer with gas burner, bag house, bucket elevators, surge hoppers, weigh-belt feeders, minerals separator screeners, loading spouts, and product silos. A truck weigh scale serves the loading area.

The frac sand mesh size gradations considered are 30/50, 50/70, and 70/140. The fine size gradation product would be in the 200/400 mesh range. Process design criteria were developed with information from Select Sands Corp’s related experience and knowledge, metallurgical test data from STIM-Lab, and sample tests from Tetra Tech.

Key Processes

• Dry primary crushing and screening
• Wet screening and first stage classification
• Wet attrition scrubbing
• Subsequent wet screening and classification stages for proppant product
• Fine product grinding circuit
• Drying, product storage and truck loading
• Water recovery via thickener and plate and frame filter press

Source: Technical Report for the Sandtown Frac Sand Property , 2015, 2015. Project website: Select Sands Corp (URL not stated)

Project website: Technical Report for the Sandtown Frac Sand Property, 2015