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Arch Dust Suppression Handbook technology found its way to the U.S. but early attempts for application in U.S. mining were not successful due to the initial capital investment required. In the early 1980's, South Africa's mining industry began to utilize the technology, followed by Australian mining facilities in the mid 80's. PRINCIPAL OF OPERATION The performance of the agglomerative dust control is based upon the principal of agglomeration. Dust particles released from the material being handled (i.e., conveyer points, screens, above and below crushers, and dump areas) are exposed to an environment that contains massive quantities of very fine water particles. This environment is similar in nature to a very wet fog often experienced on a cool summer morning. The dust particles agglomerate with the water particles, increasing in weight, then falling back to their source of origin. The percentage of water added to the material is extremely low because only the fugitive dust is effected. The control efficiency of the system can be in excess of 95% depending on the application. ENCLOSURES For maximum efficiency of agglomerative dust control, the dust source should be enclosed to provide protection from ambient conditions, especially wind. In an exposed windy area, the fog and dust particles are dispersed preventing maximum agglomeration and settlement of fugitive dust. These enclosures will vary from project to project but can be generally defined as follows: 1. Transfer points. At transfer points, enclosures should include; A) a head box with inlet strip curtain; B) a seal of some type on the underside of the feeder belt; C) a tight chute with a rock box (if the vertical drop is substantial); D) a cover over the receiving belt extending at least three belt widths downstream from the chute discharge and having a height at least equal to the belt width; and E) a cover extending back on the receiving belt behind the chute approximately one belt width. In addition, tight skirt boards are necessary for the entire length of the belt cover. Special skirt board designs are available and should be utilized if the material handled is extremely dusty. This is especially true if the vertical fall is great, or if the belt speeds are high. Strip curtains should be fitted at the front and back discharges of the cover. 2. Screens. Screens may either be totally enclosed or open above the deck. If the screen is open, the feeder belt(s) should be enclosed with a head box that extends out over the deck and distribution plate to provide a protected area for agglomeration. The area between the deck and the hopper should be sealed with rubber. Over chutes can generally be open but their receiving belts must also be treated as a transfer point. is Page 5