Lime’s Myriad Uses
Lime is the versatile mineral. Various forms of lime are used in environmental, metallurgical, construction, chemical/industrial, and other applications. The fastest growing use of lime is in environmental applications, where lime is used to comply with air, drinking water, wastewater and solid waste regulations.
However, the largest single use of lime remains steel manufacturing, where it is used to remove impurities. In construction, the dominant use of lime is in soil stabilization for roads, earth dams, airfields and building foundations. Lime can be combined with certain additives to produce other metals and is also a key ingredient in mortars and plaster in the form of lime slurry. As an additive in asphalt, lime improves its cohesion, reduces stripping and retards the aging process. There are additional chemical and industrial uses of lime, such as the manufacture of chemicals and production of precipitated calcium carbonate.
Lime in our Daily Lives
You probably woke up and showered this morning as you prepared for your day. Then you drove your car to work and had a cup of coffee as you settled in at your desk. Before your work day started, you had already used lime several times this morning.
Lime is used to neutralize and filter our drinking water. It’s also used to refine sugar, to help clarify and reduce the impurities. Lime products are used to clean water for soft drinks and even serve as a calcium supplement in your milk, yoghurt or baby food.
But it is also an additive for the asphalt we drive on, helping improve its cohesion and delaying the aging process. And a primary use remains the purification of steel and the creation of other construction products such as mortar and plaster.
Oh and do you enjoy reading the newspaper? The paper was probably bleached by calcium hypochlorite, another lime products.
Why lime is an important economic factor
EU economy – in 2011, EU lime production was around 22 million tonnes, accounting for a EUR 2 billion contribution to the EU’s GDP.
Employment – the lime sector has more than 11,000 employees. The production of cement provides about 61 thousand jobs, as well as up to 365 thousand indirect jobs related to cement production. In addition, over 305 thousand people are employed in the production of concrete.
Types of Lime products
This is the most commonly used liming material, it consists of limestone crushed to a fine powder and is usually the cheapest material for correcting soil acidity. Good quality lime has 37–40% calcium.
Lots of products that we use at home like toothpaste, shoe polish, bathroom cleaner, and baking soda contain calcium carbonate. It is also used in baby diapers, cake mixes and food coloring. The other important use is as medicine to make up for calcium deficiencies and also neutralizing stomach acid. Hard water deposits (scales) that form in the bathroom, kitchen sink are calcium deposits. Calcium carbonate is also used in the plastic and aluminum industries.
Burnt lime (calcium oxide)
Also know as quicklime, burnt lime is derived by heating limestone to drive off carbon dioxide. It is more concentrated and caustic than agricultural lime and unpleasant to handle, so is rarely used in agriculture.
Calcium Oxide (CaO) is mainly used in the production of cement. It also produces heat when it’s hydrating and forms Calcium Hydroxide (Ca(OH)2).
Hydrated lime (calcium hydroxide)
This is made by treating burnt lime with water, and is used mainly in mortar and concrete. It is more expensive than calcium carbonate.
Dolomite is a naturally occurring rock containing calcium carbonate and magnesium carbonate. Good quality dolomite has an NV of 95–98, and contains 22% calcium and 12% magnesium.
Dolomite is used as a source of magnesia (MgO), a feed additive for livestock, a sintering agent and flux in metal processing, and as an ingredient in the production of glass, bricks, and ceramics.
Their usefulness is determined by the NV and water content. If the water content is 10%, then the lime will only be 90% as effective as dry lime. You need to consider the extra costs of handling, freight and spreading.
Precipitated Calcium Carbonate
Precipitated calcium carbonate (PCC) is an innovative product derived from lime, which has many industrial applications. PCC is made by hydrating high-calcium quicklime and then reacting the resulting slurry, or “milk-of-lime”, with carbon dioxide. The resulting product is extremely white and typically has a uniform narrow particle size distribution. PCC is mainly used in the Paper, Polymer and Health Care industries.
Handling and transporting different types of lime products
The flow characteristics of different lime products vary, depending on their particle size and the percentage of humidity contained.
Handling and warehousing lime and beingg able to maintain stocks at a low cost implies using silos. Stocking lime in 25 kg. sacks or big bags on pallets is not a cost-efficient solution as a great number of square meters of expensive warehouse space is dedicated.
Loading lime can be very easy or challenging depending on the density of the product, in order to obtain significant payloads.
Bulk-Flow has designed a Screw Conveyor Loader for all kinds of bulk solids, but especially effective for medium density products that need to be transported in 20’ dv containers but do not reach the necessary payloads to make them competitive.
The Screw Conveyor Loader is a new concept as it loads by pushing the product forward and left and right; depending on the density of the product, the loading will only be finished when the container cannot be loaded further.
Unloading lime from container liners depending on the lime type requires experience and advanced bulk unloading systems as well as the liners with right technology.
Bulk-Flow has designed 2 unloading systems for hard-to-flow products:
- Unloading Screw Hopper: conceived to unload while tilting the container and feeding a rotary valve. This System together with Bulk-Flow Fluidizing Liner will unload the most difficult hard-to-flow products such as Hydrated Lime, Cement, Fluor or Titanium Dioxide.
- Tilt-Less Liner System: horizontal, mechanical unloading system that as the name says, does not require tilting. The System permits the unloading staff to control the process at all times as gravity is not a factor at unloading.
Directly connecting exporter silos to consignee silos:
containerizing lime bulk solid transports
The bulk transport process begins from the exporter’s silo and the journey to the importer’s silo can be a very complicated. The bulk solid will have to be transferred from and into several transport modes which will rise transport costs and the danger of contamination to the product.
Bulk-Flow recommends contracting a sea container, loading directly from the silo into a multilayered polyethylene film liner, closing the container doors, installing the seal and letting the shipping Co. do the rest. The importer will be the next party to open the container doors and break the seal and unload the product directly into his silo. There is no easier, cheaper and safer way of transporting bulk solids.
Minimizing handling costs and assuring the product is not contaminated by external agents and humidity offers bulk solid exporters the basis on which to develop their business. The exporter will be able to control the process and be able to inform his client where the product is and when it will be delivered to his warehouse.