Moisture Application for Dust Control

Abstract

The Bureau of Mines and several member companies of the National Industrial Sand Association have been working in many areas to reduce personal exposure to respirable dust. Areas investigated have included ventilation, improved hardware design, improved housekeeping practices, and addition of moisture to products. This article reviews information to date on various methods of using moisture to reduce respirable dust concentrations in mineral processing plants. Individual studies present an inconclusive case for additional work in this area. Together, however, these studies indicate a good potential for the development of an economical and practical plantwide dust control technique. Naturally, these techniques may only be applicable for certain mineral products.

Methods used in the individual studies to evaluate dust reductions included observation, gravimetric filter analysis, and instantaneous light-scattering methods. Various methods of moisture addition included the use of foams, steam, and water sprays. Reductions achieved were dependent on the method of moisture addition and ranged up to 90 plus percent. In general, foam and steam were nearly twice as effective in reducing dust as plain water sprays. This was attributed to increased surface area of the medium. The other significant finding was the need for thorough mixing of the product with the water.

Methods other than reintroducing moisture to a dried product material would be preferred, yet are untried. Technical and material handling problems of producing a product material with a specific moisture content may be significant. Further effort is needed to control the amount of moisture in the product and to reduce costs.