What is the standard for impurity content in calcined lime in a lime kiln
The impurity content of lime products produced by calcination is the core indicator for measuring quality, which directly affects the effectiveness and economic benefits of downstream applications. A clear and strict set of standards is the cornerstone for guiding production and safeguarding customer interests.
Core impurity types and main sources
The impurities in lime are mainly divided into the following categories:
Impurities from raw firing and overburning: caused by uneven calcination or improper process control, the raw firing core (calcium carbonate) and overburning hard core (calcium silicate, etc.) directly affect the activity of lime.
Impurities introduced by raw materials: Silicon dioxide (SiO ₂), aluminum oxide (Al ₂ O3), iron oxide (Fe ₂ O3), magnesium oxide (MgO), and clay contained in limestone raw ore.
Fuel ash impurities: When using solid fuels such as coal, their ash content is mixed into the product.
Reference to key industry standards
China has clear national standards (GB/T) for lime used in industries such as metallurgy and chemical engineering. For example, in metallurgical lime (GB/T 3286.1), there are strict limits on impurity composition according to different product grades:
The total content of acidic oxides such as silicon dioxide (SiO ₂), aluminum oxide (Al ₂ O3), and iron oxide (Fe ₂ O3) is required to be ≤ 2.0% in special grade products and ≤ 4.0% in first grade products.
The content of magnesium oxide (MgO) is usually related to the limestone source and generally requires ≤ 5%.
The over burning rate of raw materials is an important physical indicator, and high-quality metallurgical lime requires ≤ 8% or even lower.
The key to controlling impurities lies in the production process
To achieve high standards, it is necessary to control from the source:
Selected raw materials: Select high-quality limestone with high calcium and low impurities.
Optimized calcination: Using an automated lime kiln as provided by Jinyong Kiln, uniform and thorough calcination is achieved through precise temperature and air flow control, greatly reducing the rate of over firing.
Fuel management: Prioritize the use of clean fuels or pre treat solid fuels to reduce ash content.
The impurity content standards for high-quality lime are clear and strict. The core goal of modern lime kiln technology is to control these impurities at the lowest level through stable and controllable processes, thereby producing high-quality products with high activity and purity, meeting the needs of various high-end industrial fields.
