Turn Waste into Treasure! Complete Solutions for High-Value Utilization of Industrial By-Product Gypsum

Industrial by-product gypsum, also known as chemical gypsum, refers to calcium sulfate-based waste residue generated from the chemical and power industries and is a renewable resource. China produces 258 million tons of such gypsum every year, with a cumulative stockpile exceeding 1.1 billion tons. It faces prominent challenges of large existing stock, continuous new output and potential environmental risks. Its harmless, resource-based and high-value utilization stands as a core priority for solid waste treatment and the development of green low-carbon industries.

To tackle the three major problems and realize harmless, resource-based and high-value utilization of industrial by-product gypsum, Liming Heavy Industry draws on nearly four decades of accumulated grinding technology and project experience. Focusing on green transformation and high-value development, we customize integrated complete grinding solutions. Our highly efficient, energy-saving, intelligent and stable processes address the key links in the resource recovery of industrial by-product gypsum, facilitating its large-scale, resource-based and high-value utilization and setting a new benchmark for comprehensive utilization of bulk solid waste.

Classification of Industrial By-Product Gypsum

Desulfurization gypsum and phosphogypsum account for 85% of the total domestic stock. Other varieties include more than ten types of by-product gypsum such as fluorogypsum, titanium gypsum, citric acid gypsum and salt gypsum.

Processed industrial by-product gypsum (desulfurization gypsum, phosphogypsum, titanium gypsum, etc.) has formed five high-value application sectors: building materials, infrastructure construction, agriculture, ecological restoration and new materials. Covering bulk basic materials as well as high-end functional materials, it serves as a core carrier for solid waste recycling and green low-carbon transformation.

The processing technologies for industrial by-product gypsum (desulfurization gypsum, phosphogypsum, titanium gypsum, fluorogypsum, etc.) mainly center on harmless pretreatment and high-value resource utilization. Calcination and grinding constitute the core procedures for gypsum recycling. The separated two-stage process of pre-drying and calcination is designed to remove moisture, adjust gypsum crystal forms and optimize product properties.

Construction Sector Applications

Manufacture gypsum blocks, gypsum boards, plastering gypsum and gypsum mortar;

Produce self-leveling mortar, baked bricks and stabilizing base materials for highway construction;

Prepare building gypsum and high-strength gypsum products including gypsum plaster, construction putty, pressed gypsum fiberboards, ceramic decorative materials and decorative sound-absorbing panels.

Application Process of Desulfurization Gypsum and Phosphogypsum in Construction Industry

01 Pre-drying

High-moisture gypsum such as desulfurization gypsum undergoes rapid pre-drying to remove free water and avoid caking and blockage of subsequent calcination equipment.

02 Calcination & Dehydration

Under constant temperature, dihydrate gypsum loses crystal water and transforms into hydraulic hemihydrate gypsum, namely building gypsum powder.

03 Grinding & Modification

Calcined gypsum is ground efficiently to uniform fineness with simultaneous modification to stabilize product performance.

04 Cooling & Aging

High-temperature gypsum powder is cooled and homogenized for more stable phase composition and performance, then delivered to finished product silos for standby application.

Cement Industry

Used as cement retarder to control cement setting time and replace natural gypsum;

Added as special mineralizer for cement production in clinker calcination to optimize crystal formation of clinker minerals;

Adopted for co-production of sulfuric acid and cement, generating industrial sulfuric acid and cement clinker simultaneously in one kiln.

Application Process of Industrial By-Product Gypsum in Cement Industry

01 Precise Raw Material Batching

Take industrial by-product gypsum as the main raw material, proportionally mix coke/anthracite as reducing agent, clay/fly ash as silico-aluminous component and iron powder as mineralizer.

02 Raw Meal Preparation

Fully mix and grind proportioned materials to produce qualified raw meal powder with standard fineness and components.

03 High-Temperature Calcination in Rotary Kiln

Raw meal powder is fed into the rotary kiln for calcination and decomposition reactions under a specific high-temperature reducing atmosphere of 1200–1300°C.

04 Flue Gas Acid-Making Process

High-temperature flue gas with high SO₂ concentration discharged from the kiln tail undergoes purification, conversion and absorption processes in sequence to produce industrial sulfuric acid.

05 Clinker Cooling and Discharge

High-temperature clinker discharged from the kiln head is rapidly cooled by a grate cooler to obtain stable and qualified cement clinker.

Production of High-End Calcium-Based Fillers

Through refined deep processing, new functional calcium fillers including ultrafine Type I anhydrous calcium sulfate (crystal-transformed calcium) and high-end functional reinforcing filler calcium sulfate whiskers can be produced. They can replace traditional fillers such as ground calcium carbonate, precipitated calcium carbonate, talc powder and barium sulfate, boasting far higher added value than gypsum cement retarders and ordinary building gypsum raw materials.

Process for Producing High-End Calcium-Based Materials

Raw material impurity removal and purification

High-temperature calcination for crystal transformation / directional controllable crystallization

Ultrafine grinding: 800–3000 mesh

Powder modification and homogenization

Tailored to the characteristics of industrial by-product gypsum such as phosphogypsum, desulfurization gypsum and titanium gypsum, Liming Heavy Industry provides an integrated full-process grinding solution covering pretreatment, pre-drying, calcination and dehydration, grinding & modification, cooling & aging, as well as eco-friendly storage and transportation.

LM Vertical Roller Mill integrates drying, grinding, powder classification and conveying functions, making it an ideal core equipment for large-scale, low-energy gypsum milling production.

MTW6X Intelligent European Mill with full thin-oil lubrication system adopts complete thin-oil lubrication and intelligent control system, enabling precise control over finished powder fineness and activity to guarantee stable quality for high-end building materials and fine chemical industries.

Supported by mature processes and core equipment, the complete solution addresses industrial bottlenecks including high moisture and viscosity of raw materials, unstable product quality, excessive energy consumption and heavy environmental compliance pressure, and realizes efficient large-scale, high-value and resource-based utilization of solid waste.

Core Advantages of Gypsum Grinding Solution

Strong Process Adaptability

Compatible with multiple types of by-product gypsum including desulfurization gypsum and phosphogypsum; production lines of various capacities can be customized as required.

Remarkable Energy Saving & Cost Reduction

Waste heat recycling is adopted, cutting overall energy consumption by over 30% compared with traditional processes and greatly lowering production costs.

Stable Product Quality

Precise control over fineness and activity, meeting high-standard requirements for cement retarders, building gypsum, self-leveling materials and other products.

Eco-Friendly & Compliant with Environmental Regulations

Fully enclosed dust-free production; on-site disposal of solid waste to eliminate stockpiling pollution at the source.

Intelligent & Efficient Operation & Maintenance

Intelligent PLC central control system ensures high equipment stability and supports unattended continuous production.

With customized integrated grinding equipment solutions featuring core models such as LM Vertical Roller Mill and MTW6X Intelligent European Mill with full thin-oil lubrication, Liming Heavy Industry has delivered a host of benchmark projects for phosphogypsum, desulfurization gypsum, fluorogypsum and other by-product gypsum across China. Widely deployed in building materials and new materials industries, the complete production lines operate stably with outstanding resource recovery benefits and have won wide acclaim from customers.

We offer one-stop customized solutions ranging from single machines to full turnkey production lines tailored to the actual working conditions and capacity demands of each project.

Liming Heavy Industry provides customers with EPC general contracting services and adheres to the philosophy that "Customers' success equals our success". Boasting a professional design institute team, we deliver full-process one-stop services covering project planning and design, equipment selection and configuration, installation and commissioning, as well as post-operation maintenance. Drawing on extensive project experience in grinding equipment manufacturing, we have accelerated the efficient delivery of numerous gypsum milling projects and achieved multi-dimensional optimization of construction cycles and operating costs.

The resource utilization industry of industrial by-product gypsum has entered a new refined, stepped and high-value development mode. Having long specialized in solid waste processing equipment, Liming Heavy Industry has mastered the full set of processes including pretreatment, calcination and crystal transformation, and ultra-fine grinding of industrial by-product gypsum, meeting the processing requirements of various by-product gypsum such as desulfurization gypsum and phosphogypsum. Aligned with the national goals of carbon peaking, carbon neutrality and zero-waste city construction, we drive industrial upgrading through equipment innovation, shift the industry from passive waste disposal to active resource creation, empower green coordinated development across multiple industries, and foster sound and sustainable industrial circular economy.