Assessment of the Spraying System Impact at the Preparation Stage of Iron Ore Concentrate Products

Abstract

Introduction. Harmful components of ore dust, formed during the unloading of products in the preparation of iron ore concentrate (PPIOC) at the mixing stage, cause damage to both workers and equipment. To address this issue, liquid aerosol spraying using nozzles with large diameters (>20 μm) is used. However, this method proves ineffective in capturing fine-dust particles. Therefore, enhancing the efficiency of the dust deposition method through PPIOC dust spraying becomes a pressing challenge. The aim of this study is to investigate the impact of the Dry Fog technology, generating liquid droplets up to 20 μm in size, during the unloading stage of PPIOC at a mining and metallurgical enterprise in the precipitation of suspended fine-dust particles. The primary goal of this research was to assess the effectiveness and potential advantages of applying the Dry Fog technology for dust spraying with subsequent precipitation, as this technology has not been previously applied to PPIOC dust.Materials and Methods. The experiment on the PPIOC dust deposition was conducted in a specially designed laboratory setup. Through physical modeling in the laboratory setup, parameters of the precipitation process were obtained. Subsequently, the results were analyzed to understand the dependence of dust precipitation over time, taking into account the influence of the Dry Fog technology. An experiment program was developed for physical modeling. According to the devised program, dust was uniformly loaded into the interior of the laboratory setup (from the top), distributed in the air stream throughout the volume of the setup by a fan, and an instrument located at the bottom recorded changes in concentration over time. Experiments on dust precipitation were then conducted using liquid spraying (filtered water as the liquid) introduced into the setup through nozzles generating droplets with sizes of 10 and 15 μm, concurrently with the loading of dust into the laboratory setup. The effectiveness of the Dry Fog technology in the deposition of PPIOC dust was determined visually and further analyzed based on a comparison of graphs. The dynamics of changes in the average dust concentrations depending on time was studied both during precipitation without spraying and using the Dry Fog technology. During the experiment, the characteristics of the microclimate inside the laboratory setup (humidity, temperature and air velocity) and the parameters of two nozzles — their operating pressure and the supplied liquid spraying time — were recorded.Results. The comparison of the results showed a reduction in the dust precipitation time by 40 % and 75 % when using nozzles with sizes of 10 μm and 15 μm, respectively.Discussion and Conclusion. The experiment results confirm the effectiveness of the Dry Fog technology for PPIOC dust precipitation during unloading at the mixing stage. Fundamental findings have been obtained, providing a basis for further assessment of the efficiency of dust precipitation with the additional application of pulsating ventilation. In such a combination, an additional 20–25 % increase in precipitation efficiency is anticipated compared to the results presented in this article. The obtained results will support the justification of rational parameters and the implementation of the described method in production to enhance dust precipitation efficiency. Additionally, they will aid in developing a methodology to accelerate the PPIOC dust precipitation using the pulsating ventilation method.