Industrial by-product gypsum—also known as chemical gypsum—is a calcium sulfate-based waste residue generated during production processes in the chemical and power industries; it is classified as a renewable resource. With an annual output of 258 million tons and a cumulative stockpile exceeding 1.1 billion tons, China faces a situation characterized by "three highs": high existing inventory, high annual growth, and high potential risks. Consequently, the harmless treatment, resource recovery, and high-end utilization (the "three-pronged approach") of this material have long been a focal point for both the government and enterprises.
To effectively address the industry challenges associated with these "three highs" and the "three-pronged approach," Liming Heavy Industry has leveraged nearly four decades of expertise in grinding technology and global project experience. Aligning closely with industry trends toward green transformation and high-value development, the company has tailored an integrated, complete grinding solution. This system—characterized by high efficiency, energy conservation, and intelligent, stable operation—streamlines the critical stages of resource recovery. It establishes a mature technical pathway to "treat waste with waste" and "turn waste into treasure," thereby supporting the comprehensive, high-end, and large-scale utilization of industrial by-product gypsum and setting a new paradigm for the comprehensive use of bulk solid waste.
Domestic stockpiles consist primarily of desulfurization gypsum and phosphogypsum, which together account for 85% of the industry total; the remainder comprises over ten other varieties, such as fluorogypsum, titanogypsum, citric acid gypsum, and salt gypsum.
A by-product of power plant desulfurization, primarily composed of calcium sulfate dihydrate. It has low impurity levels and a moisture content of 12%–15%, but is highly cohesive and prone to agglomeration.
A waste residue from phosphoric acid production; it is acidic, contains phosphorus and fluorine impurities, and poses a risk of water and soil pollution when stockpiled.
Titanogypsum, fluorogypsum, salt gypsum, citric acid gypsum, mirabilite gypsum, copper gypsum, abrasive tool gypsum, etc.
Processing technologies for industrial by-product gypsum (such as desulfurization gypsum, phosphogypsum, titanogypsum, and fluorogypsum) primarily focus on "harmless pretreatment" and " high-value resource utilization." Calcination and grinding are the core stages of this utilization process; specifically, the two-stage separation process—comprising pre-drying followed by calcination— aims to remove moisture, alter the gypsum crystal form, and enhance product performance.
Supported by the core principle of the "sulfur-calcium double circulation", the complete process generates sulfuric acid and cement clinker simultaneously in one kiln. It fully recycles all sulfur and calcium elements contained in industrial by-product gypsum, forming a typical technical route for recycling and resource utilization of bulk solid waste.
Take pre-treated industrial by-product gypsum as the main raw material, proportionally add coke / anthracite as reducing agents, clay / fly ash as silica-alumina components, and iron powder as mineralizer.
Fully mix and grind the proportioned materials to produce qualified raw meal powder with standard fineness and chemical composition.
Raw meal powder is fed into the rotary kiln and undergoes calcination and decomposition reactions under a specific high-temperature reducing atmosphere of 1200–1300°C.
High-temperature flue gas with high SO2 concentration discharged from the kiln tail sequentially goes through purification, conversion and absorption processes to produce industrial sulfuric acid. The acid can be directly recycled for upstream phosphorus chemical production, realizing closed-loop utilization of sulfur resources.
High-temperature clinker exiting the kiln head is rapidly cooled by a grate cooler to obtain qualified cement clinker with stable quality.
Rapidly remove free water from high-moisture gypsum to prevent caking and material blockage during calcination.
Under constant temperature conditions, dihydrate gypsum loses crystal water and transforms into hydraulic hemihydrate gypsum, namely building gypsum powder.
Calcined gypsum is ground to uniform fineness with high-efficiency milling equipment, and modified simultaneously to stabilize product performance.
Cool and homogenize high-temperature gypsum powder to stabilize its phase composition and properties, then deliver it to the finished product silo for standby application.
Through refined deep processing, industrial by-product gypsum can be made into new functional calcium fillers: ultrafine Type II anhydrous calcium sulfate (crystal-transformed calcium) and high-end functional reinforcing filler calcium sulfate whiskers. They can replace conventional fillers such as ground calcium carbonate, precipitated calcium carbonate, talcum powder and barium sulfate, boasting far higher added value than gypsum used as cement retarder or ordinary building gypsum raw material.
Tailored to the characteristics of industrial by-product gypsum including phosphogypsum, FGD gypsum and titanium gypsum, Liming Heavy Industry provides an integrated full-process milling solution covering pretreatment, pre-drying, calcination & dehydration, grinding & modification, cooling & aging, and eco-friendly storage & transportation.
The LM Vertical Roller Mill integrates drying, grinding, powder classification and conveying into one single unit, serving as the ideal core equipment for large-scale, low-energy-consumption gypsum powder production.
The MTW 6X Fully Thin Oil Lubricated Intelligent European Grinding Mill is equipped with a full thin oil lubrication system and intelligent control system, enabling precise regulation of finished powder fineness and activity, and guaranteeing stable quality for high-end building materials and fine chemical industries.
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Applicable to various by-product gypsum including FGD gypsum and phosphogypsum; production lines of different capacities can be customized as required.
Waste heat recycling is adopted, cutting overall energy consumption by over 30% compared with traditional processes and greatly lowering production costs.
Fineness and activity are precisely adjustable to meet high-standard requirements for cement retarders, building gypsum, self-leveling materials and more.
The whole process adopts closed dust-free operation, enabling on- site disposal of solid waste and eliminating stockpiling pollution at the source.
PLC intelligent central control system ensures high equipment stability, supporting unattended continuous production.
From planning to delivery, our integrated EPC service minimizes risk, accelerates timelines, and ensures predictable outcomes for every project.
Our company takes charge of the overall project planning and on‑site implementation. The client is only responsible for high‑level, principle‑based management and objective control. The vast majority of responsibilities and risks shall be borne by our company.
We can provide customers with one‑stop and complete professional solutions. This addresses the challenges faced by clients, especially pure‑investment‑oriented customers, such as lack of technical expertise and limited understanding of equipment. It helps clarify project requirements and positioning, and greatly cuts clients’ costs in terms of capital, manpower and energy.
For projects featuring large‑scale investment, long construction periods, relatively complex technologies and high uncertainties, a lump‑sum fixed‑price contract with fixed construction duration facilitates cost and schedule control and helps minimize investment risks.
Our company takes full responsibility for design, production, installation, commissioning and other phases. We exercise full‑process control over every link. Clients can monitor project progress in real time, with guaranteed engineering quality and greatly shortened construction period.
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