At the end of 1990, with the rapid development of high analysis phosphate compound fertilizers, output from the supporting wet-process phosphoric acid grew rapidly. Output of phosphogypsum as a by-product was more than 3 Mt each year. Finding a solution to the problem of phosphogypsum discharge and its re-utilization was increasing in urgency.  From 1983, the former Shandong Wudi Sulphuric Acid Plant (now the Main Plant of Lubei Chemical Industry), the Jinan Yuxing Chemical Plant and the Chemical Research Institute of Shandong Province jointly completed an industrial experiment of combined production of sulphuric acid and cement with 7,000 t/y of gypsum salt.  Based on the previous industrial experiment with gypsum salt in 1990, the former Ministry of Chemical Industry invested in the main plant of Lubei Chemical Industry in Shandong and linked up with a 30,000 t/y ammonium phosphate plant to establish an installation that utilized phosphogypsum to produce 40,000 t/y of sulphuric acid and 60,000 t/y of cement (called the 3-4-6 project in short). This built up the experience of using phosphogypsum as a raw material in the combined production of sulphuric acid and cement. This was the first set of ammonium phosphate - sulphuric acid - cement combined production plants. Verification of the results indicated that the production capacity of the plant exceeded the designed capacity by 15%.  In 1999, the Main Plant of Lubei Chemical Industry’s 15-20-30 project, that is, the 150,000 t/y of AP, 200,000 t/y of sulphuric acid and 300,000 t/y of cement project went into operation. The establishment of such installations achieved economic, social and environmental benefits. They complied with the principles of a recycling economy, an ecological technique that makes full use of resources.  The technology of combined production of cement and sulphuric acid by phosphogypsum developed and designed in China has the following characteristics: The dehydrate phosphogypsum should meet the following requirements of SO3 = 40%, SiO2 = 8%, P2O5 = 1%, F = 0.35% and the phosphogypsum does not require purifycation. It is not necessary to use the foreign technique of calcination at high temperature for the dehydration and drying of dehydrate phosphogypsum or dehydration of phosphogypsum to hemihydrate phosphogypsum to reduce energy consumption.  The heat consumption in making the cement clinker by a rotating kiln is lower than the 7,500 kJ/kg in other countries.