Optimizing XO Throughput at Imerys

Author

Derek Beasley, Kennesaw State UniversityFollow
Brennan Chandler, Kennesaw State UniversityFollow
Baris Erarslan, Kennesaw State UniversityFollow
Cynthia Grogin, Kennesaw State UniversityFollow

Date of Submission

Fall 12-7-2025

Project Type

Senior Design

Department

Department of Industrial and Systems Engineering

Committee Chair/First Advisor

Sohyung Cho

Secondary Advisor

Valentina Nino

Abstract

This project is conducted in collaboration with Imerys to optimize the performance of the VSI (Vertical Shaft Impactor) system at their Plant 4 facility, focusing on improving the production of XO, a fine material used in products such as textured coatings, acid neutralization, and water filtration systems. The VSI operates continuously, producing several materials at the Marble Hill, Georgia location, including #1 Chip, #2 Chip, OZ, XO, Z, and 30–50. The main focus of this project is to increase the throughput of XO, as it requires both throughput improvement and product quality consistency to meet growing market demand. Imerys’ quality specification for XO focuses on particle size within a target range and minimal production of oversized material. This project focuses on the development and implementation of a key solution to boost XO production: a 10% increase in the Variable Frequency Drive (VFD)/rotor speed on the VSI. Before and after the change, material samples are collected and analyzed using Gilson and Ro-Tap screening machines to measure particle size distributions, while throughput is verified via rate checks in tons per hour (TPH). The VSI currently operates at a baseline rotor speed of 1,404 RPM (78.5% capacity) and processes rock material from the feed conveyor through crushing and screening operations. The project’s primary goals are to increase XO throughput, improve particle size consistency, and reduce bottlenecks, all while maintaining product quality. The project involves a series of process improvements. To establish a baseline for production, the VSI was first operated at 1,404 RPM (78.5% capacity). A total of 20 samples were collected, 10 feed samples before the VSI and 10 product samples after. Particle size distribution was measured using the Gilson and Ro-Tap screening machines, with each sample tested for the industry-standard duration of seven minutes. The Gilson machine quantified coarser fractions, while the Ro-Tap assessed finer material, including XO, which passes through 16–32 mesh screens. Following baseline measurements, the rotor speed was increased by 10% to 1,544 RPM (85.5% capacity), and an additional 20 samples were collected before and after the VSI. Using the same screening methods, results showed XO production increased from 12.82% at baseline to 15.68% after the speed adjustment, representing a 22.31% gain. Simultaneously, larger and less desirable fractions were reduced, with #2 Chip dropping from 2.87% to 2.01% (−29.97%) and #1 Chip decreasing from 11.33% to 7.90% (−30.27%), demonstrating improved crushing efficiency and a reduction in oversized material. The OZ fraction experienced a slight decrease from 18.42% to 17.87% (−2.99%), indicating minimal impact on this category. Meanwhile, finer fractions increased, with Z rising from 8.28% to 10.52% (+27.05%) and #30–50 increasing from 5.96% to 7.08% (+18.79%), confirming a more uniform and consistent product output overall and allows for less recycling of material. Planned future improvements included installing new XO screens with a reversed mesh configuration to enhance separation efficiency, rebalancing the VSI to enable further throughput optimization, upgrading Elevator 43, which transfers rock material from the rock belt to the first screening process, and ultimately increasing the rock belt speed from 20 tons per hour (TPH) to 20 TPH to boost overall throughput. These steps were sequenced to ensure that every process could handle higher tonnage per hour (TPH) before additional modifications were implemented. Overall, the VFD/rotor speed adjustment on the VSI successfully increased XO throughput, reduced material recycling and bottlenecks, and enhanced overall process efficiency.