The S. Howes Continuous Mixer (or Pug Mill) has been used to mix a variety of polymers or resins into pre-treated or washed frac sand. Where frac sand is used as a “proppant” the S. Howes continuous mixer can add liquid or solids free flowing materials to a silica based material such as sand. Liquids can be pumped in through manifolds using a wide selection of dispersing nozzles. Or, a customized inlet can be manufactured to accommodate any type of dry agent. The adjustable paddles and angle of the mixer can be modified to process the frac sand. S. Howes has built mixers out of a variety of abrasive resistant materials such as AR 400 and AR 500. The mixer is heavy duty and robust, suitable for mining and drilling environments.