Lime Slaking Basics

Lime slaking is a critical industrial process, playing a pivotal role in water treatment, non-ferrrous mining, flue gas treatment, chemical manufacturing, and a range of other applications. Understanding the basics of lime slaking, including its significance and the different types of slakers used, is an important step in enhancing the effectiveness of various processes that rely on slaked lime.

What is slaking?

Slaking is the process of adding water to quicklime (calcium oxide) to produce hydrated lime (calcium hydroxide). The slaking reaction is exothermic, meaning it generates heat and causes the quicklime to crumble, forming the hydrated lime or slaked lime. When this reaction occurs in a hydrator, the amount of added water is carefully controlled, resulting in the formation of a dry powdered hydrated lime. When quicklime is slaked in a slaker, a greater amount of water is introduced, producing a liquid suspension of hydrated lime, also known as lime slurry.

What is slaked lime?

Slaked lime is the product produced when quicklime (calcium oxide) is mixed, or slaked, with water. The slaking reaction produces hydrated lime (calcium hydroxide) in the form of hydrate, a dry, white powder, or as a liquid lime slurry. Slaked lime is a strong alkaline substance and is often used to raise pH levels in water and soil.

Basic uses for slaked lime

Slaked lime in the forms of lime slurry and hydrated lime are used in various applications, including:

• Water treatment to adjust pH levels and remove impurities.
• Construction for making mortar, plaster, and whitewash.
• Flue gas treatment (FGT) to reduce acid gases and heavy metals.
• Agriculture to treat pH levels of soils or absorb/neutralize odors from animal waste.
• Chemical Manufacturing for use as a reagent in various chemical processes.

Components of a Lime Slaking System

A lime slaking system typically includes several key components to ensure efficient and controlled slaking of quicklime. Here are the main components:

1. Quicklime Storage and Handling: Facilities for storing and handling quicklime before it is fed into the slaking system.
2. Dust Collection: Equipment to capture and manage dust generated during the handling and processing of quicklime or hydrated lime.
3. Feed & Conveying: Equipment for ensuring smooth material flow and precise and consistent dosing.
4. Water Supply System: A system to provide the necessary water for the slaking process, often including pumps, valves, and flow meters to control the water flow.
5. Slaker: The primary equipment where quicklime is mixed with water to lime slurry. Slakers typically incorporate mixing blades or agitators to ensure thorough mixing and a temperature control system to help monitor and control the slaking reaction. There are different types of slakers, such as detention slakers, paste slakers, and ball mill slakers.
6. Lime Slurry Storage and Pumping: Facilities for storing and handling the produced slaked lime, which include agitated storage tanks and pumps.

These components work together to ensure the efficient and safe production of slaked lime. For more information, learn about Carmeuse Systems lime slaking systems.

What is a lime slaker?

A lime slaker is a piece of equipment that mixes water with quicklime (calcium oxide) to produce a hydrated lime slurry (calcium hydroxide). Slakers use paddles, mixing blades, grinding media, or other agitators to thoroughly and evenly mix the lime and water. The slaking process is exothermic, meaning it generates heat. Lime slakers are designed to control this reaction and ensure the efficient production of a lime slurry at the desired concentration. There are different types of lime slakers, including:

1. Batch Slakers: This type of slaker produces slurry in discrete batches and are best suited to applications where the needed slurry production rate is relatively low.
2. Detention Slakers: These slakers hold the quicklime and water mixture for a set period, known as retention time, to ensure complete reaction. Unlike in batch processes, detention slakers can produce a continuous supply of lime slurry.
3. Paste Slakers: These slakers have a smaller footprint and also operate continuously.
4. Ball Mill Slakers: These slakers use grinding media to aid in the slaking process, producing a fine, uniform lime slurry. There are both vertical and horizontal ball mill slaker orientations, but both types are typically used for applications requiring a high slurry production rate.