Three types of sugar are produced: standard, raw, and refined. ISA is the only producer of refined sugar in Nicaragua. White sugars are marketed under the Azúcar del Ingenio and Azúcar San Antonio brands.
The following sub-products are also obtained during sugar manufacture:
Process syrups: Used for manufacturing alcohol (rums and ethanol).
Bagasse: Used as biomass fuel in boilers to produce steam for sugar and ethanol manufacture and electric power cogeneration.
Sugar mud: Used as a fertilizer in field irrigation water.
Production capacity is approximately 245,000 metric tons of sugar, which allows NSEL to supply 50 percent of the Nicaraguan sugar market and export 60 percent of total production.
The process of transformation of cane into sugar begins at the mills. We have two milling lines (tandems): one with mills only and another with mills and diffuser, which process an average 15,000 tons per day with high energy efficiency levels, low sucrose losses and little loss of time.
Before being processed in the mills, cane is washed and passed through a shredder that cuts and de-fibers it into small pieces less than 2” long without extracting the juice.
At the mills, 4 hammers mechanically press the cane to extract the juice. Water is added to each hammer to dissolve the sucrose that would otherwise be lost along with the bagasse.
Juice flows on to the clarification process, while bagasse (cane fiber and rind) is used as fuel in the boilers. The steam generated in the boilers is used to propel the generator turbines, which, in turn, generate electric power for other activities. Surplus energy is sold to the national grid.
Juice impurities are removed in the clarification process. Milk of lime is added to form complex high molecular weight compounds. The cane juice is then heated to 102-105° C and goes to the clarifier, where mechanical decantation takes place. Insoluble solids are separated by sedimentation and a clear juice is extracted continuously.
The sugar mud resulting from the juice clarification process is sent to the filtration area to retrieve as much sucrose as possible. The mixture passes through rotating vacuum filters that separate the juice from the sugar mud. The sugar mud is sent to the field as fertilizer and the juice returns for further processing.
The evaporation process seeks to remove 75% of the water from the clarified juice. A series of interconnected evaporators are used that enables evaporation in the first evaporator to be used as heating steam for the second and so forth. The manufacturing process is optimized by extracting steam from the evaporation equipment, multiplying the energy performance of the steam coming from the boilers. At this stage, condensed water is obtained for use in boilers and factory processes.
The evaporation area is equipped with an automatic process control system and state-of-the-art instruments and equipment enabling digital control of juice and steam flows, and levels of material in the equipment.
The syrup resulting from evaporation is clarified through a floating system that removes impurities that could not be sedimented during juice clarification.
The clarified syrup is concentrated in vacuum pans until it becomes saturated. Sucrose crystals are formed by controlling oversaturation. The process takes place in a cascade using 3 continuous 14-cell vacuum pans. The end result of this cooking is raw sugar (for export or animal feed production) and white sugar used for direct consumption or as raw material for refined sugar production. The difference between both products is the degree of sugar purity. The crystallization area also has an automated computer control system.
The crystallization product passes through centrifuges where crystals in the cooked mass are separated from the surrounding syrup. Centrifugated sugar can be the final product or it can be returned to become the core of larger sugar grains. Similarly, the syrup can be recirculated or taken out of the process as a byproduct.
In the last stage of the process, sugar is dried and packed in different presentations. Part of production is directly delivered to customers and the other part is stored in warehouses to be marketed in the off-harvest season.
Part of the sugar obtained from cane is sent to the Refinery where it is first melted, filtered, and bleached with activated carbon.
Subsequently, it goes through crystallization, centrifugation, drying, and packing processes. Refined sugar is mostly consumed by industrial customers as the quality is much higher than sugar directly produced from cane. This sugar is also packed in 2-kg and 800-g bags for household consumption.
White sugar produced by ISA is enriched with vitamin A, according to Ministry of Health regulations.