A system for mixing, for example, salt with water to make brine, includes a mixing vessel removably mounted within a bulk vessel. The mixing vessel is provided with a divider/filtration wall separating a front portion, where solid granular material is provided and mixes with a liquid for purposes of dissolving the solid granular material into the liquid, and a rear portion. The mixing vessel is provided with an agitation pipe along a floor thereof, and is shaped to minimize settled granular material from collecting at the base of the mixing vessel. The divider/filtration wall serves to prevent overflow, includes one or more screens to allow liquid, but prevent granular material larger than the pore size of the screens, to pass from the front portion to the rear portion, and in the event of overflow, minimize turbulence in material passing over the divider/filtration wall, all of which promote delivery of a uniform distribution of dissolved material to the batch tank. In the case of salt brine production, a wireless salinity sensor can accurately measure salt concentration in real time at a variety of depths.