Laboratory Testing Procedures
Process: First, the material requires an assessment, beginning with bulk density.
Purpose: The material bulk density helps define the volumetric flow of material within the screener and thus the resulting bed depth.
Process: Use a riffle splitter prior to feed analysis, continue to split the feed until you have a small enough sample for analysis (approximately 100 grams).
Purpose: Testing requires a good representative sample, splitting the sample ensures the full spectrum of the material is represented in the analysis. This helps with screen selection, final product analysis, and machine recommendation or max loading calculations.
Process: Use the Gradex, Ro-Tap, or other analysis method to find the particle size distribution (PSD) of the feed.
Purpose: PSD is a breakdown of the sample that defines the relative amount, typically by mass, of particles present according to size. Specific attention is given to understanding near size particles at desired separation points.
Process: Once the PSD is known, you can then select the proper screens based on the customers separation and product specifications.
Purpose: Select the best screen opening and wire diameter to maximize the product recovery efficiency, while also meeting the product quality specificaitons.
Process: Using the data from steps 1-3 select the appropriate machine model or calculate the desired max loading. Next, perform the screening test using the selected screens and machine model/max loading.
Process: Weigh the separated fraction including overs, intermediates (if any) and fines to determine the percentage of each.
Purpose: Determine the raw product efficiency of the separation.
Process: Analyze the separated fractions to get the PSD of each fraction.
Purpose: To determine product loss, product quality and product recovery efficiency.
Process: Review the PSD of fractions to confirm separations meet customer specifications and product recovery rates. If the test is successful, a lab test report and flow diagram are generated. If following the test the product does not meet customer specifications then a new test will be run, changing the parameters such as screen mesh size, mesh cleaning bals, machine selection, etc.
Purpose: Clearly identify the separation performance achieved by Rotex laboratory testing and the ability to meet customer requirements while maximizing product recovery. Rotex lab testing results will be guaranteed for field applications, assuming all variables are consistent with lab testing.
*Max loading is the maximum recommended pounds per hour per square foot that can be successfully screened with the given material. Max loading is determined by material properites, historical test data and application expertise.
Purpose: To replicate the screening scenario and criteria to determine feasibility. Material flow, separation performance, and bed depth are visually monitored during the test. Machine loading, screen blinding, and ball selection are analyzed before, during, and after testing.
*A typical application may contact 5% overs, 85% intermediate and 10% fines
*Product recovery efficiency is a ratio measuring the percentage of on spec product that comes out of the screener relative to the percentage of product that was available in the feed.