Lime softening is a common process used in many sectors to soften hard water and involves the raising of the pH of the water and precipitation or absorption of calcium. There is a normal softening and also the enhanced version, which is raised once at the initial stages and then again at a second stage. This increases pH levels to over 10.0 and eradicates any magnesium and uranium components.
The difference is that with the normal softening process it removes up to 80 % of uranium, however with the enhanced version eradicates over 90% of the uranium, as well as other harmful substances such as manganese, arsenic, tannins, lead, chromium, nickel, barium, cadmium and iron. According to this source from the United States Environmental Protection Agency (EPA), the drawback however is that this can be an expensive process as it uses specific technology which monitors the chemistry and is done in a few plants’ refineries.
The process of softening aids in removing the alkalinity and hardness of certain soils, it is sometimes necessary to add a deterioration agent into the material and finished water to abide by compliance regulations and prevent possible contamination from copper and lead.
During the process various chemicals are used that can soften water and remove the carbonate hardness of it, soda ash is one of them. When there is an excess of slaked lime, the need to neutralize acids is imperative. But because of the expense and limitations, many industries have found other alternatives to using caustic soda. These include lime products.
Why Caustic Soda Is Not Recommended
Caustic soda has both advantages and disadvantages. It is available in a variety of formats such as solution and solid-state, come in 20% or 50% and helps to adjust the pH levels accurately. Not only is it easy to handle but in excess, it also stores better than most other lime products. Lime, when mixed with water, often produces large amounts of sludge.
With the caustic soda, however, there is minimal sludge produced, and it is not as harmful to your eyes and skin when handled. All this may sound ideal, but this product is very expensive in comparison to the calcium products mentioned above, as the price increases by weight. So the more you need, the higher the price you pay for it per ton.
Calcium Lime Products – The Ideal, Safest and Cost-Effective Solution
Because these products have been used in various applications for many diverse reasons, it has become a popular solution for sectors that require a need for pH adjustment, and flocculation and coagulation as well as metals removal. Switching to calcium products is usually the ideal alternative. Lime products are commonly available in four different formats:
Limestone or CaCO3
As a common and unrefined alternative, it forms the basis of most other lime products. It comprises a solid stone of various ranges and sizes. This has been used to neutralize acids in many specific applications and industries. It is a natural substance that is mainly composed of calcium carbonate (CaCO3) and can also be referred to as aragonite or calcite.
It does however contain significant amounts of dolomite or magnesium carbonate and is found in clay, quartz, pyrite, iron carbonate and various other minerals: https://www.britannica.com/science/limestone and as a commercial alternative, it is used in agriculture and glass factories. In some instances, the construction and building industry use it too, to create monuments, flooring for both interiors and exteriors of buildings. In this context, it is used to neutralize acids in the soil allowing plants and vegetation to grow effectively.
Quicklime, or CaO
This is another type of limestone that requires processing inside a rotary kiln. It is commonly found in stores in a solid format and is mixed with water to create a consumer-friendly substance. This can also be used for the purpose of acid neutralization and also added to large sources of water such as lakes and rivers as part of the treatment and to adjust the pH to an optimal level. It is also used in the mining industries and steel industries as well.
These products are not as hazardous as caustic soda, and are economically viable for many, as a caustic soda alternative solution to an alkaline agent. It has a stronger neutralizing capacity which means less goes a long way, and as such is cost-effective as well as does not necessitate wastage. Specific equipment is needed to produce the substance; however, it is much easier to handle than other forms of extractions.
While the majority of the above have their advantages and disadvantages, any calcium or lime product, no matter form it is available in, seems to be the best solution to adjusting the pH of components and is a lot safer than caustic soda. It is cost-effective in the long run too and the price does not increase when using large amounts of it, either.