Innovative gravity separation for sustainable utilization of mineral resources

Recent technological advancements have enabled the commercialization of a novel gravity separation device, the packed column jig (PCJ). The PCJ offers several distinctive advantages: an exceptionally long (virtually unlimited) separation zone, compact footprint, minimal water consumption, chemical-free operation (making it environmentally friendly), high throughput, and the ability to process a wide range of particle sizes, including very fine particles. Significant breakthroughs have been achieved to enhance the PCJ’s robustness for industrial use. A major advancement is the effective resolution of a potential plugging issue through a combination of four strategies: (1) adoption of new packing materials, (2) innovative packing design, (3) variable feed-point configurations and (4) a novel discharge system. Another critical improvement is the development and integration of a fully automated computer control system, which also contributes to preventing plugging. Introduction This paper presents three case studies demonstrating the application of the PCJ in significantly improving resource utilization efficiency and reducing the environmental footprint of phosphate mining, particularly in processing tailings and byproducts from the industry. Fig. 1 A phosphogypsum processing strategy for total consumption with gravity separation using PCJ. Key results Upgrading of phosphogypsum. The global phosphate industry produces more than 150 Mt of phosphogypsum each year. Phosphate producers are under increasing pressure to identify practical and sustainable uses for this byproduct. One promising solution is the utilization of phosphogypsum in construction materials, which could significantly reduce its accumulation. Figure 1 presents a process flowsheet for phosphogypsum purification, which combines gravity separation using PCJ with flotation.Pilot-scale testing of this integrated process has successfully produced upgraded phosphogypsum suitable for various construction applications. The treatment reduced soluble phosphorus content from 0.89 percent to 0.04 percent and increased whiteness from 39 to 87. Fig. 2 PCJ pilot plant installed in Florida. Removing dolomite from Florida high-dolomite phosphate pebbles. Encouraged by promising laboratory results, the Florida Industrial and Phosphate Research Institute undertook a major pilot PCJ testing program using a pilot plant with a capacity of 1 t/h (Fig. 2). Based on initial laboratory testing results, the feed preparation scheme for the PCJ pilot testing was selected as follows: (1) Screen the test sample at 5 mm, with the –5 mm portion screened into 5 by 2.36 mm (8 mesh), 2.36 by 1.4 mm (14 mesh) and –1.4 mm fractions simultaneously. (2) Crush the +5 mm portion of the test sample and screen into 5 by 2.36 mm (8 mesh), 2.36 by 1.4 mm (14 mesh) and –1.4 mm fractions simultaneously. Table 1 summarizes the continuous, long-hour pilot testing results. Conclusion Fig. 3 Proposed scheme for further pilot testing. The results for the –2.36 +1.4 mm size fraction are highly encouraging; however, the concentrate grade — particularly the MgO content — from the –5+2.36 mm fraction was not acceptable. Based on a comprehensive analysis of laboratory and pilot-scale testing, as well as the size distribution of high-dolomite pebbles and their crushed fractions, an optimized processing scheme has been developed, as shown in Fig. 3. In this proposed approach, only two size fractions are subjected to jigging using the PCJ. The –70 mesh fraction from the crushed pebbles is excluded from further processing due to its high MgO content (7.7 percent) and relatively minor phosphate loss (14.37 percent P2O5), making recovery economically unjustifiable. Selected references Yang DC (1996) Device and process for gravitational separation of solid particles, US Patent No. 5,507,393, April 16 Nicol S (1998) A case study in the implementation of novel technology: teetered bed separators. Aust Coal Rev Dai Q (1999) Simulation of packed column jigging. Master’s thesis, West Virginia University, Morgantown, WV, USA Yang DC, Bozzato P, Ferrara G (2003) Iron ore beneficiation with packed column jig, J Miner Mater Charact Eng 2(1):43–51 Zhang Zheng S, Song W, Feng C, Moudgil B, Xiao W, Zhang D (2019) Promising options for solving the dolomite problem of the Florida phosphate resources—a brief review, Min Metall Explor 36 (1):117–129

Innovative gravity separation for sustainable utilization of mineral resources

Authored by: Patrick Zhang, Aaron Medley, Wending Xiao, Dapeng Zhang and David Yang

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