Rock Products

JUN 2019

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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34 • ROCKproducts • June 2019 T he very basic function of frac sand is to create and main- tain passageways needed for the harvesting of either natural gas or crude oil. There are three basic types of prop- pants that are being used: natural silica sand resin coated silica sand, and ceramic beads. The wet processing of frac sand involves taking natural silica sand proppants from the point of a mined stockpile of silica sand to the stockpile that feeds the product for final sizing. The basic function of a wet frac sand processing plant is to provide clean sand that is free of clays in the total range of size classifications required by the end user. This size range will vary from one producer to another. While there are a variety of configurations you could use to process the frac sand, there are five key factors that all producers should consider when planning and constructing a frac sand plant. 1. Prove Deposit: Size and Uniformity The ideal frac sand particle needs to be composed almost entirely of silica, be well rounded (weathered), structurally sound (able to withstand high pressure) and be free of clay impurities. API specifications define the required character- istics of frac sand and is used around the world to qualify sand for use in fracking. This set of standards defines size ranges and tolerances. Tested qualities include mineral composition, compressive strength, acid solubility, conductivity, turbidity, roundness and sphericity. Defining these allows for clear and consistent grading of the vastly different sand produced throughout the world. It is important to prove reserves for accurate valuation of a frac sand operation. The most accurate ROI calculations are based on comprehensive drill data throughout the breadth of the deposit rather than testing of a single sample. This is common sense to some and overkill to others, but knowledge of the depth, size and mineral the deposit is comprised of gives confidence to investors and insight to your frac sand planning. The number and location of boreholes required can vary widely among different deposits depending on their size and uniformity, so it is important to consult experts in the field during this process. Once this data is gathered, a knowledge- able equipment manufacturer or a mining engineering firm should be able to provide assistance in calculating the cost of running and maintaining equipment so that your profitability expectations are met or exceeded. A potential advantage to proper valuation of a deposit is determining potential byproducts in addition to the pri- mary frac sand products. These may be a valuable mineral or simply a size fraction that may otherwise go to waste. Identifying the full range of minerals in a deposit with the help of a geologist is the best way to maximize a mine site's profitability. Natural silica sand deposits can exist above or below the water table, therefore the mining methods can range from dredging operations to mining via standard excavators. Some of the deposits above the water table can exist as liberated sand particles or in deposits that require blasting (bumping) and the use of primary crushers, such as jaw crushers. The crusher can be run in either closed-loop (screens used to close circuit) or open-loop systems depending on the nature of the deposit (ease with which silica particles are liberated) and the efficiency of the silica liberating circuit. It is impera- tive that methods used to liberate the silica particles do not crush or create fractures in the individual silica particles. 2. Design a Flexible Processing Plant Final plant designs should be based on run-of-mine feed, but it is important to take into consideration the entire breadth of potential feeds when designing a system. The borehole data from a proven reserve should be ana- lyzed and (discounting overburden) the best and worst feeds should be considered alongside the run of mine feed. This comparison allows for equipment to be selected that can handle anything you throw at it. It also gives insight into production rate variation from different parts of the pit. In sand deposits, the feed gradations can be compared in an Excel spreadsheet by analyzing the production rate, fine rejected, how many products are being made, and the Get Your Frac on Track 5 Factors to Consider When Building a New Frac Sand Plant. By Mark S. Kuhar Frac Sand

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