The molecular structure effects of starches and starch phosphates in the reverse flotation of quartz from hematite

Starch vs. tannin as biodegradable reagents for ultrafine hematite depression

Enrichment of ultrafine liberated valuable minerals from their associated gangue phases is one of the emerging investigation topics within mineral processing and recycling. Using green flotation reagents and turning processes into eco-friendly systems is also one of the challenges in the green transition of ore beneficiation plants. Starch and Tanin as biodegradable depressants for hematite depression have been commercially used in various iron ore processing plants. However, their depression effects on ultrafine particles were not systemically assessed and compared. To fill this gap, this investigation examined the effects of starch, tannin, their mixtures (different ratios), and their different conditioning sequence on the floatability of ultrafine quartz and hematite (- 15 µm). Since the macromolecular polymer of these biodegradable depressants can bind particles together and flocculate them, turbidity analyses were used to assess their optimum ratio for hematite depression without affecting quartz floatability. Turbidity analyses provided a mixture of tannin and starch might enhance the flotation separation of quartz from hematite. Starch could flocculate ultrafine hematite particles, while tannin could disperse ultrafine quartz particles. Floatability experiments indicated that starch had the highest performance in hematite depression (lowest effect on quartz particles) compared to other conditions. Surface analyses (zeta potential and FTIR) proved floatability outcomes and highlighted starch had stronger adsorption on the hematite surface than tannin.

Composite starch films as green adsorbents for removing benzo[a]pyrene from smoked sausages

Benzo[a]pyrene (BaP), which is emitted during the processing of smoked sausages, accumulates in sausages and poses a serious threat to human health. This study focused on the removal of BaP from sausages and accompanying particulate matter (PM) during the smoking of sausages by films formed by combining corn starch (CS) with K-carrageenan (KC)/sodium alginate (SA). Initially, the effects of different additions of KC and SA on the rheological analysis, thermogravimetric analysis (TGA) and film-forming properties of the composite films were investigated. The BaP reduction capacities of CS-KC and CS-SA composite films in sausage were 41.1%-47.0% and 54.2%-56.5%, respectively, because the three-dimensional mesh structure of the composite films provided a large number of adsorption sites. Finally, kinetic studies demonstrated that BaP control in composite films is mainly achieved by intraparticle diffusion. Therefore, due to its excellent recyclability and biodegradability, composite starch film has a promising application in smoked meat products.

Research on Coal Gangue Recognition Based on Multi-source Time-Frequency Domain Feature Fusion

The over-exploitation of resources caused by the increasing coal demand has resulted in a sharp increase in solid waste emissions mainly gangue, which has made the burden on the environment, economy, resources, and society of our country heavier. In order to achieve a balance between energy consumption and solid waste emission in the process of top coal caving, this study carried out coal gangue recognition research based on multi-source time-frequency domain feature fusion (MS-TFDF-F). First, the process of coal gangue symbiosis and the harm of gangue in top coal caving are analyzed, and the fundamental method of comprehensive treatment of gangue is put forward, which is the accurate recognition of the coal gangue interface. Second, by building a top coal caving simulation test bed, the MS signals generated in the caving process of the coal gangue mixture with a gangue content of 0-100% are collected and the TFDFs are extracted. Third, the MS-TFDF-F-based coal gangue recognition model is established. Then, the recognition effect of the two TFDF-F sample sets was compared, and the results show that the time-frequency domain feature selection fusion method (TFDFS-FM) has higher accuracy. On this basis, this paper studies the variation law of the number of sensors on the coal gangue recognition accuracy of MS information fusion. Finally, the economic, social, environmental, and resource benefits of the model are qualitatively described. The final results show that the MS-TFDF-F-based coal gangue recognition model has the strongest recognition ability when fusing six sensor signals, and the recognition accuracy reaches 99% under the AdaBoost algorithm. The establishment of this model brings huge benefits to China's environment, economy, resources, and society, and it is helpful to realize the balance between loss reduction mining and solid waste emission reduction in the process of top coal caving.

Advancing phosphate ore minerals separation with sustainable flotation reagents: An investigation into highly selective biobased depressants

Froth flotation has been a commonly employed technique to enrich natural ores by removing impurities based on the surface properties of minerals. This process involves the use of various reagents, including collectors, depressants, frothers, and activators, which are often chemically synthesized and may represent environmental risks. Therefore, there is a growing need to develop biobased reagents that offer more sustainable alternatives. The aim of this review is to provide a comprehensive assessment of the potential of biobased depressants as a sustainable alternative to traditional reagents in selective flotation process for phosphate ore minerals. To achieve this objective, the review investigates the extraction and the purification methods of different biobased depressants, analyzes the specific conditions for reagent interaction with minerals, and assess the biobased depressants' performance through a range of fundamental studies. These studies aim to (i) provide a better understanding of the adsorption behavior of some biobased depressants onto the surfaces of apatite, calcite, dolomite, and quartz comprised in different mineral systems by measuring their zeta potential and analyzing their Fourier transform infrared spectra before and after contact with these reagents, (ii) determine the depressants' adsorption amounts, (iii) evaluate their effect on the contact angle of bare minerals, and (iv) assess their ability to inhibit the flotation of the studied minerals. The outcomes revealed the potential use and the promising applicability of these unconventional reagents since their performance is comparable to that of conventional reagents. In addition to their good effectiveness, these biobased depressants have the added advantages of being cost effective, biodegradable, non-toxic, and ecofriendly. Nevertheless, further research and investigations are required to improve the selectivity and, consequently, the effectiveness of biobased depressants.