Calcium carbonate, or CaC03, comprises more than 4% of the earth’s crust and is found throughout the world. Its most common natural forms are chalk, limestone, and marble, produced by the sedimentation of the shells of small fossilized snails, shellfish, and coral over millions of years. Although all three forms are identical in chemical terms, they differ in many other respects, including purity, whiteness, thickness and homogeneity. Calcium carbonate is one of the most useful and versatile materials known to man.
Some typical uses for CaC03
Paper, Plastics, Paints, and Coatings:
Calcium carbonate is the most widely used mineral in the paper, plastics, paints and coatings industries both as a filler, and due to its special white colour as a coating pigment. In the paper industry it is valued worldwide for its high brightness and light scattering characteristics and is used as an inexpensive filler to make bright opaque paper. Filler is used at the wet-end of paper making machines and calcium carbonate filler allows for the paper to be bright and smooth. As an extender, calcium carbonate can represent as much as 30% by weight in paints. Calcium carbonate also is used widely as a filler in adhesives, and sealants.
Personal Health and Food Production:
Calcium carbonate is used widely as an effective dietary calcium supplement, antacid, phosphate binder, or base material for medicinal tablets. It is also found on many grocery store shelves in products such as baking powder, toothpaste, dry-mix dessert mixes, dough, and wine. Calcium carbonate is the active ingredient in agricultural lime, and is used in animal feed. Calcium carbonate also benefits the environment though water and waste treatment.
UWT (UK) Ltd’s partner SN Engineering received a brief to design and deliver a facility that would accept and store the raw bulk material before being conveyed to the grinding and classification process. Following processing, the sub 75µm finished product was to be conveyed and stored in a pair of 2600m³ bulk storage silos. UWT (UK) Ltd were partnered with SN Engineering to supply the process control for continuous monitoring of the silo levels using Nivobob series and overfill protection via the use of Rotonivo 3000 series of the rotary paddle switches.
The Nivobob plumb-bob systems were selected due to their ease of installation, ease of commissioning and complete reliability. The Rotonivo 3000 series was selected as a back up system to protect against overfilling, this rotary paddle switch offers complete security in durability and ease of use.
· A level control product was required that could guarantee a trouble free operation and straightforward commissioning. The bulk solids material in this application presented the challenges of:
· Lime powder – an aggressive and very dusty material
· Aggregates – aggressive, high load
· Discontinuous level measurement of bulk goods and interface measurement
· Simple and reliable measuring principle
· Sensor weights in various designs suitable for every application
· Insensitive to dust, dielectricity, conductivity, humidity, caking
· Easy installation, maintenance-free operation
· Very precise results covering large measuring ranges
· Suitable in hazardous locations (dust explosion)
· Detection of solids in liquids
· Suitable for interface applications
· Increased durability via brushless motor also with high measuring frequency
· Large measurement distances and long intervals between
· A multitude of different process connections and accreditations ensure that Nivobob is suitable for the international market
· Rotating paddle switch suitable for most bulk goods
· Simple and reliable measurement principle, maintenance free
· Insensitive to dust, electrical charge, adhesion, temperature and pressure
· Suitable for Hazardous Locations (dust explosion)
· Small and compact design, requires little space
· Swivelling housing for simple installation
· Robust die-cast aluminium housing
· Enclosure IP 66
· Variety of supply voltages and process connections available
The first phase of commissioning for this new carbonate processing plant took place in October 2012. The client has acknowledged complete satisfaction with the quality of service and products delivered by SN Engineering and partner, UWT UK Ltd.