Calcium carbonate (CaCO₃) is one of the most popular mineral fillers in the plastics industry. In this application example, the customer needs to transfer 4.5 tons (10,000 pounds) of calcium carbonate per hour from a storage bin to a filter receiver located atop a rotary valve, for use in extruding polypropylene and calcium carbonate at a plastic compounding facility. The facility is situated at an elevation of 305 meters (1,000 feet), with an average daily temperature of 29.5°C (85°F) year-round. Significant differences in particle characteristics between submitted samples led to the selection of distinct equipment components as well as a redesign of the system’s overall dimensions.

The design of feeding or pneumatic conveying systems is significantly influenced by the particle shape, size (aspect ratio), particle size distribution, as well as the roughness, hardness (abrasiveness), and density of bulk solids. In the case of calcium carbonate, these characteristics can vary widely depending on the source of individual samples and the production process. Pneumatic conveying systems typically consist of five essential components: an air compressor, conveying pipelines, a distribution device, a material-gas separator, and a control system.

The calcium carbonate feeding system—selecting the right feeding system for each specified calcium carbonate sample—is primarily determined by two key variables: the characteristics of the mineral filler (such as particle size and shape, gas permeability, bulk density, and natural angle of repose) and the required feeding rate. The Loss-in-Weight (LIW) feeder offers a fully enclosed solution for both raw material and dust, delivering optimal feeding-rate performance to ensure consistent product quality. LIW feeders come in a variety of configurations, with hopper sizes, feeding mechanisms, and weighing bridges tailored specifically to match the properties, flow behavior, and desired flow rates of the material being fed.

Our years of experience, combined with our expertise in process engineering design, ensure that our plants and systems deliver high levels of operational reliability and safety, as well as maximum availability.