Preparation and performance of starch-based cross-linked network structured dust suppression foams for complex climatic conditions.

In complex environmental applications such as rain erosion and high-low temperatures in open-pit coal mines, the curing layer after dust suppression foam treatment is relatively poorly tolerated, resulting in poor dust suppression. This study is aimed at a high-solidification strong weather-resistant cross-linked network structure. First, oxidized starch adhesive (OSTA) was prepared by the oxidative gelatinization method to reduce the effect of the high viscosity of starch on the foaming effect. Then, OSTA, polyvinyl alcohol (PVA) and glycerol (GLY), were copolymerized with the cross-linking agent sodium trimetaphosphate (STMP), and compounded with sodium aliphatic alcohol polyoxyethylene ether sulfate (AES) and alkyl glycosides (APG-0810), a new material for dust suppression in foam (OSPG/AA) was proposed and its wetting and bonding mechanism was revealed. The results show that OSPG/AA has a viscosity of 5.5 mPa·s, a 30-day degradation of 43.564 % and a film-forming hardness of 86HA; through simulated tests in open-pit coal mine environments, it was found that the water retention of OSPG/AA is 40.0 % higher than that of water, and the dust suppression rate of PM10 is 99.04 %. The cured layer can adapt to temperature changes from -18 °C to 60 °C and remains intact after rain erosion or 24 h immersion, exhibiting good weather resistance.

Influence law of structural parameters of pressure-swirl nozzle on atomization effect based on multiscale model.

The dust pollution at the fully mechanized heading face has seriously threatened the health of the miners. As the main technical means, the outer spray of a roadheader has the problems of small coverage of the fog field and low dust removal efficiency. Based on the multiscale swirl atomization model of LES-VOF, this study simulated and analyzed the atomization process of the nozzle. The influence law of the diameter, the length and the circulation area ratio of the swirl chamber, and the swirl core angle on the swirl number and atomization effect were determined, and the nonlinear function relationship between variables was obtained. With the help of the BP neural network model, a new type of swirl nozzle is developed which is suitable for the outside spray system at the fully mechanized heading face. The experimental results show that the error between the predicted results of the new swirl nozzle and BP network model is less than 15%, the atomization angle θc is 24.2°, the average particle size D32 is 64.43 µm, and the effective range Reff is about 2.1 m. At the same time, the total dust removal efficiency and respirable dust removal efficiency of the new swirl nozzle at the driver's place are 61.10% and 63.85%, respectively, which are 21.69% and 20.92% higher than the original nozzle.

Preparation and properties of modified starch-based low viscosity and high consolidation foam dust suppressant.

Aiming at the high-concentration dust pollution in open-pit coal mines, a foam dust suppressant with low viscosity and consolidated coal dust is developed. In order to reduce the limited effect of binder viscosity on the foaming ability and wettability of foam, tapioca starch is oxidized with Cu2+/H2O2 System in this study to reduce the molecular weight of the polymer and prepare materials with high consolidation and low viscosity. The dust suppression performance of the sample is measured, and the microscopic adsorption mechanism of the dust suppressant is investigated by molecular dynamics simulation. The results show that the oxidized starch adhesive solution consists of 20 g tapioca starch, 0.88 ml hydrogen peroxide, 2.4 g sodium hydroxide, and 0.48 g copper sulfate, which need to be diluted to 10 times the original volume, and 1 g of surfactant (sodium fatty alcohol polyoxyethylene ether sulfate/alkyl Glycoside=1:4) is added to prepare a new foam dust suppressant. The viscosity is 2.6 mPa·s, the foaming multiple is 6.25, the contact angle is 13.73° at the first second, the hardness reaches 70.75 HA, and a dust suppression rate of 98.17% for PM10. The dust suppressant can effectively suppress coal dust.

Synthesis and performance determination of a glycosylated modified covalent polymer dust suppressant.

Traditional polymer dust suppressants are limited due to environmental pollution, while polymer gels have attracted attention due to the advantages of environmental protection and good biocompatibility. The purpose of this research is to prepare a new type of dust suppressant with a gel network structure, which was synthesized from soybean protein isolate and glycosylated with xanthan gum. The experimental results showed that the product obtained by reacting 0.2 % xanthan gum and 0.1 % soybean protein isolate at 90 °C for 4 h has the best binding effect on coal dust, and the coal husk hardness can reach 83 HA. The microscopic reaction and structure of the product were analyzed by infrared spectroscopy, X-ray diffractometer, and scanning electron microscope, and the results revealed the structural change and specific reaction process of the product. In addition, through molecular dynamics simulation, the dust suppression effect was confirmed and the mechanism of action between dust suppressant and coal was revealed. The performance test of the dust suppressant showed that its viscosity is 23.4 mPa·s, the contact angle at 1 s is 10.01°, the PM10 dust suppression efficiency can reach 98.10 %, the water retention is 44.44 % higher than that of water, and thermal stability is improved.

Study on the coal dust deposition fraction and site in the upper respiratory tract under different particle sizes and labor intensities.

In order to study the dust exposure amount and coal dust deposition rule of coal miners under different labor intensity in coal mine environment, an airflow-particle two-phase coupling calculation model of human upper respiratory tract was established based on Euler-Lagrange framework, and the airflow field in the upper respiratory tract and the characteristics of coal dust deposition were simulated and studied. By comparing the experimental data, the relative error of simulation is in the range of 1.5 %-11.2 %. The results showed that the total deposition fraction of 1 µm dust was the smallest (0.61-1.20 %), and was relatively less affected by respiratory intensity, and the overall distribution was uniform. When the dust particle size increased to 7.07 µm, the total dust deposition fraction in the nasal cavity, pharynx and larynx was in the range of 11.10 %-20.91 %, and increased with the respiratory intensity. When the dust particle size was large, the dust particles of 20 µm and 80 µm were mostly concentrated in the front of the nasal cavity, and the deposition amount of 80 µm dust was about 99.52 %. It was found that with the increase of dust particle size or the increase of labor intensity, the possibility of dust being transported into lungs became smaller. The fitting function of 7.07 µm dust escape rate and labor intensity was obtained, for example, Y7.07µm = 91.73-0.22n (n is labor intensity), and the escape rate of dust with 7.07 µm particle size was up to 88.90 %. Most of them escape from the upper respiratory tract and enter the lungs, which provides theoretical guidance for quantifying the accumulated dust exposure amount in the lungs and monitoring respiratory dust concentration.

Review and prospects of mining chemical dust suppressant: classification and mechanisms.

Coal mine pollution is a serious threat to the mine safe production and occupational health of miners. Chemical dust suppression can effectively reduce the concentration of coal dust and suppress the re-entrainment of dust. This paper discusses the research progress of three kinds of traditional dust suppressants: the wetting-type, cohesive type, and condensed type. In order to meet dust suppression and environmental protection requirements, 7 kinds of new type dust suppressants, such as compound, ecological environmental protection, polymer, functional, microbes, and enzymes, have been developed by the predecessors. And all kinds of dust suppressant mechanism and main performance index have been summarized. Through the analysis of the research results from 1985 to 2021, it is found that the compound and environment-friendly dust suppressants have gradually become the research focus in this field, accounting for 17.93% and 26.21% of the total number of achievements. In the recent 5 years, new materials, such as microbe suppressant, urease suppressant, and nanomaterials, have gradually emerged. Because of their natural and environmental protection characteristics, it could be predicted that they will become the future development trend in this field. However, there are still some problems to be improved, such as expensive price and complex preparation technology.

Supported Liquid Membranes Based on Bifunctional Ionic Liquids for Selective Recovery of Gallium.

In this work, separation and recovery of gallium from aqueous solutions was examined using acid-base bifunctional ionic liquids (Bif-ILs) in both solvent extraction and supported liquid membrane (SLM) processes. The influence of a variety of parameters, such as feed acidity, extractant concentration and metal concentration on the solvent extraction behavior were evaluated. The slope method combined with FTIR spectroscopy was utilized to determine possible extraction mechanisms. The SLM containing Bif-ILs demonstrated highly selective facilitated transport of 96.2% Ga(III) from feed to stripping solution after optimization. During the evaluation of the separation performance of SLM for the transport of Ga(III), in the presence of Al(III), Mg(II), Cu(II) and Fe(II), 88.5% Ga(III) could be transported with only 6% Fe(II) and a nil quantity of other metals co-transported. SLM exhibited excellent long-time stability in five repeated transport cycles. Highly selective transport and separation performance was achieved using the SLM containing Bif-ILs, indicating considerable potential for application in Ga(III) recovery.