In hard rock mining, sensor-based sorting can be applied as a pre-concentration method before the material enters the mill. X-ray transmission sensors have been explored in mining since 1972. Sorting ore of acceptable grade and waste material before processing at the mill can reduce the amount of tailings per unit of valuable metal in the mining operation and have many economic benefits. Ore samples used in this paper are from a polymetallic carbonate replacement deposit (gold-silver-lead-zinc sulphide) in Southeast Europe. This paper focuses on how the Dual-Energy X-ray Transmission (DE-XRT) data is generated and used for ore characterization and sortability for this sulphide ore. The method used in the DE-XRT analysis in this project is based on the dual-material decomposition method, which is used in the medical industry for radiology. This technique can distinguish sulphides from non-sulphides. However, the correlation developed between the DE-XRT response and the metal content is lacking. As a result, the DE-XRT response can only classify the material effectively but cannot reliably predict the metal content.

In this paper, the process of direct reduction roasting using magnetic separation to produce direct reduction iron (DRI) from high-phosphorus oolitic hematite, using coal slime and blast furnace dust as reductant, is investigated. The possible use of slime coal and blast furnace dust as reductant and the dephosphorization behavior during the process of direct reduction was studied. Experimental results showed that both blast furnace dust and coal slime can be used as reductant under certain conditions in the process. The dephosphorization mechanism of blast furnace dust and coal slime were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDS). A DRI with 91.88 wt. % iron grade, 88.38% iron recovery and 0.072 wt. % P can be obtained with 30 wt. % blast furnace dust as reductant. The program not only used blast furnace dust but also recovered iron from blast furnace dust and high-phosphorus oolitic hematite. The analysis results revealed that phosphorus is distributed in gangue mineral and fluorapatite when blast furnace dust is used as reductant. Phosphorus-bearing minerals were not reduced to phosphorus element when the blast furnace dust was the reductant, but part of the fluorapatite reduced to phosphorus which smelt into metallic iron with coal slime as reductant. This led to a high phosphorus content of DRI. This research could provide support to the idea concept for recycling of carbon-containing solid waste and to assist the effective recovery of refractory iron ore by direct reduction–magnetic separation.

Sorting coal using x-ray transmission sensors has been explored since 1972 by Jenkinson et al. Coal sortability is assessed using washability derived from dual-energy X-Ray transmission (DE-XRT) system. Coal sorting is considered to be dry separation of coal that can be carried out before coal is send to the processing plant. It can act as deshaling/destoning process or it can also be used to selectively mine shallow coal seams to avoid overburden contamination hence dilution. There are a few commercial concepts in the coal industry which utilizes the XRT sensors to sort the coarse particle coal. In order to define final product quality in terms of ash as well the efficiency of any separation based on density such as yield, washability is used to determine the separation process parameter such as density of separation, e.g. specific gravity. Washability characteristics have been traditionally assessed using the float-sink (washability) tests. These analyses determine how much of coal can be separated from associated rock (mineral matter) in liquids of different densities. However, the test work requires a wet processing where organic liquids, referred to as heavy liquids are used. The test work is very time consuming as it requires significant amount of time to complete full washability for a wide spectrum of coal particles. To avoid using toxic chemicals and save time, the DE-XRT can easily become an alternative method to assess the washability of coarse coal before the coal is processed by sorting to establish separation parameters and obtain information about the yield of clean coal of desired quality in terms of ash content. In this project in order to assess effectiveness of DE-XRT for sorting and at the same time to derive the washability data for the coarse coal, the test work has been designed to test various lithotypes identified from coarse coal sample. As a result, the test work included classification of coal lithotypes (larger pieces of coal of certain petrographic composition), density measurement using both DE-XRT and float-sink tests and ash analysis. The results are compared to float-sink tests for coarse coal fractions obtained by proxy washability analysis derived from pycnometry. Similar to float-sink tests, the DE-XRT can estimate a relative density by measuring the attenuation of x-rays from two different energy levels. The paper explains the basics of the DE-XRT analysis and its data processing methods to determine the relative densities and how to derive washability curves and density of separation for coal sorting. The basic principle of dual-material decomposition is adopted from Dual-Energy CT in the medical industry where the sum of each vector provides a proportion of the two material.

Accurate information on coal washability characteristics is crucial for optimizing beneficiation processes. This study investigates the use of dual-energy X-ray transmission (DE-XRT) in predicting ash content and specific gravity (S.G.) by employing a structured calibration approach. A total of 36 coal samples from a British Columbia mine were analyzed using DE-XRT, S.G. measurements, and ash analysis. A controlled calibration method was developed by systematically varying rock-coal (rock-ash forming minerals) ratios to establish reliable DE-XRT response trends. Results demonstrated strong correlations between DE-XRT-derived relative density and rock mix ratios, confirming its capability in estimating coal quality. The generated washability curves closely followed traditional sink-and-float results, particularly at higher ash contents, validating DE-XRT's potential in coal sorting. These findings highlight DE-XRT as a viable tool for real-time coal quality assessment during its beneficiation. Future work should focus on refining calibration techniques and improving detection in extreme density ranges to enhance prediction accuracy and sorting efficiency.