Mixing equipment dust minimization

Up to the late 1960s, only dry formulations of atrazine were available. Ciba-Geigy Corporation later developed the first water-based, flowable concentrate formulation of an herbicide, AAtrex 4L, which was approved on January 15, 1970. This development launched a new era in herbicide formulation technology. The water-based formulation improved the manufacturing process, minimized dust, was easier to package and to load into application equipment, and easier to mix. Gradually, more and more farmers who used atrazine switched to the liquid formulation, which is now the preferred formulation. 

A calcium peroxide chlorine scavenger is now mixed into the emulsion donor charge to control chlorine produced in the DAVINCH vessel during operations. This reduces the HCl in the offgas and thereby minimizes pitting and corrosion in piping and other equipment. As a result, the chlorine concentration in dust in the inner vessel doubled and the HCl concentration in the stack (prior to release to the atmosphere) was reduced from 180-200 ppm to 0.1-0.5 ppm. Between 6 and... 

Mixers receive most of their exposure as a result of splashes, powder spills, contact with encrusted equipment, overflows, and other random events. None of these are predictable, yet the magnitude of these potential exposures obliterates the long term contribution of vapors, low level dust clouds, etc., when statistical correlations are made. Consequently, the most practical approach would be to revamp the mixing process so that the opportunities for accidents are minimized, recognizing that this short time-span operation should be conducted under strict protective conditions. 

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