Frit manufacture

Raw materials for enamel frit manufacture Oxides, carbonates, nitrates and fluorides of ... 

In frit manufacture the raw materials of the particular frit recipe are intimately mixed, fed into the furnace and smelted. Various furnace types can be used ... 

Generally, soluble materials are more effective as micronutrient sources than are insoluble ones. For this reason, many soil minerals that contain the micronutrient elements are ineffective sources for plants. Some principal micronutrient sources and uses are summarized below. In this discussion the term frits refers to a fused, pulverized siUceous material manufactured and marketed commercially for incorporation in fertilizers. Chelates refers to metaHoorganic complexes specially prepared and marketed as especially soluble, highly assimilable sources of micronutrient elements (see CHELATING agents). 

Another large appHcation is as an ingredient in the production of charcoal briquettes. The amount of sodium nitrate used in charcoal briquette manufacture depends on the type and amount of wood and coal used. Typically charcoal briquettes contain up to almost 3% sodium nitrate. Sodium nitrate is also used in the manufacture of enamels and porcelain as an oxidizing and fluxing agent. In porcelain—enamel frits used for metal coating, the amount of sodium nitrate in a batch varies with the various metal bases to be coated, typically from about 3.8 to 7.8 wt %. 

The preparation of the enamel slip includes ball milling the frit and raw materials to the appropriate consistency. Frit is the glassy raw material that makes up the backbone of porcelain enameling. Most frit is manufactured outside the operation but some plants do include captive operations. Other raw materials, such as clay and gums, are mixed into the frit by the ball mill that then releases this mixture to the coating operation.3 6... 

The main bottleneck in the further development of CEC is related with the state of the art of the column manufacturing processes and the robustness of the columns/instrumentation. Moreover, evidence to demonstrate reproducibility of separations from column to column still has to be established. The formation of bubbles in the capillaries due to the Joule heating and variations in EOF velocity on passing from the stationary phase through the frit and into the open tube is still very challenging in packed column CEC. A way to overcome this problem is to use monolithic columns or apply open tubular CEC [108]. Currently, many efforts are placed in improving column technology and in the development of chip-CEC [115] as an attractive option for lab-on-a-chip separations. 

In both types of liquid-membrane ISEs, the membrane acts as an inunis-cible phase boundary between the aqueous and non-aqueous solutions inside the ISE (see the schematic diagram presented in Figure 3.13). In order to minimize mixing, the liquid membrane is held in place by an inert, porous material such as a rigid glass frit or a flexible synthetic polymer - the choice will depend on the manufacturer rather than on experimental considerations. 

Anhydrous borax is used in the manufacture of glasses, glass wool, and metallurgical fluxes. Other uses are in enamels, frits, and glazes. It also is applied in fertilizers. 

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