When making MCP1, this way, the fir

When making MCP1, this way, the first mixer reactor is set up to make MCPa. This follows the discovery that making MCP1 directly produces a product with greater tendency to stickiness and caking in storage, whereas hydrating MCPa produces a superior product [48]. The feed control is set up to achieve a Ca/P molar ratio of between 1:2 and 1:8, as discussed earlier, and the reactor temperature set at 140°C. This temperature is achieved through a combination of using the heat of dilution of the phosphoric acid and heat of reaction. At this temperature, much of the water of dilution and reaction is driven off as steam. If calcium carbonate is used as a dry feed, then carbon dioxide is also driven off in the reaction. A careful design of the venting of the reactor is essential to avoid losing a lot of material to the vent filtration system. As depicted in Figure 5.7, the phosphoric acid, normally 85% H3PO4, is mixed in a static mixer with water and then sprayed onto the reaction mass in the mixer reactor. The mixer reactor is drawn as a continuous ribbon blade mixer; however, several different types are used including kneaders and plow share mixers. Both batch and continuous operations are possible.
One of several quality and specification measures for many