Abstract: The present invention includes a partially continuous countercurrent process for converting gypsum, by reaction with ammonium carbonate, to products of ammonium sulfate and calcium carbonate by introducing the reactants into reactors, mixing the reactants for a predetermined amount of time, employing a novel combination of countercurrent flows coupled with the reactors operated in a batch manner with process recycle of liquids, removing materials from the reactor and separating solids from solutions wherein no reactants are added during the removal process and thus the reactants have sufficient time to react and ensure the desired degree of reaction, yield and purity of product calcium carbonate and ammonium sulfate while minimizing the reaction time.

Abstract: A continuous countercurrent flow process for converting FGD gypsum to ammonium sulfate and calcium carbonate including countercurrent flows with internal recycle of liquids to maximize the purity of reaction products while minimizing reaction times, and further include embodiments of the process that provide a yield of both ammonium sulfate and calcium carbonate to be 97 to 100%, and embodiments that provide for processes having a total time of reaction being 8 to 12 minutes, the invention further including processes for removing contaminants from the FGD gypsum employing an acid rinse process and/or a slurry tank reactor process.

Abstract: A continuous countercurrent flow process for converting FGD gypsum to ammonium sulfate and calcium carbonate including countercurrent flows with internal recycle of liquids to maximize the purity of reaction products while minimizing reaction times, and further include embodiments of the process that provide a yield of both ammonium sulfate and calcium carbonate to be 97 to 100%, and embodiments that provide for processes having a total time of reaction being 8 to 12 minutes, the invention further including processes for removing contaminants from the FGD gypsum employing an acid rinse process and/or a slurry tank reactor process.

Abstract: A hydraulic system for controlling a gang of lawn mowers including a hydraulic pump and a multi-section valve and hydraulic motors driving the mowers. Hydraulic cylinders are also included in the system, for raising and lowering the mowers, and a check valve is connected with the cylinders for controlling the lowering of the mowers. The main valve is arranged with a plurality of spools which control the aforementioned functions and with the spools being set by means of a single handle so that the operator can perform the aforementioned functions through maneuvering the single handle for each set of hydraulic motors and cylinders. A hydraulic flow restrictor is included in the system for reversing the motors at a speed slower than the forward motor speed, for a slower reverse rotation of the mowers, such as for back-lapping of the mowers.

Abstract: A mobile sweeper having a body and ground-engaging wheels. The body defines a trash compartment which has a bin having a top plate such that trash can be swept into the bin and also thereabove onto the top plate. Sweeping reels are disposed in front of and rearwardly of the body compartment for sweeping the trash into and onto the bin. A closure or door is included in the body and can be opened for dumping the trash from the compartment, and a hydraulic system is employed for opening the door and for effecting the dumping of the trash.