The modified phosphogypsum was obtained by calcining the mixture of phosphogypsum and alkaline modified reagent at appropriate temperature. The properties of Portland blend cement were superior to Portland cement clinker when modified phosphogypsum was used as regulating retarder, because the modified phosphogypsum had the characteristic of regulating setting time and increasing of physical strength in each curing age which was verified by experiment results. Alkaline accelerators reacted with micro constituent of phosphogypsum to form infusible dissolution or volatile products, thus the activity of phosphogypsum and hydration procedure was improved.

When capacitors are used for reactive power compensation under harmonic load, the harmonic current would be seriously amplified or even resulting resonance． The problem of the harmonic in the device for capacitor reactive power compensation was analyzed． The working principle of the device for reactive power compensation and harmonic suppression was introduced．

This paper introduces the design method of control system based on profibus fieldbus． DP bus interface and motor control of kiln are designed by using SPC3 chip， dual single Micro－chip AT89S52 and AT90S8515． The hardware and　software based on bus system is given by the author．