Materials like coal, cement raw materials and iron ore are food of industry. Material elements are important indexes and parameters of production process of products like electric power, cement, steel and so on. At present, the analysis of material elements commonly adopts artificial sampling, sample charting and analysis, which have error in sampling and sample charting, low analyzing speed, limited analyzing indexes and is easily influenced by anthropogenic factor. For example, poor quality coal and coal gangue are always blended during the verification of factory entry coal, which is difficult to be verified by traditional sampling and sample charting, so heavy loss occurred to users. During the production process of thermal power plant, quality of fed furnace coal is key parameter influencing safe and economic operation of furnace. For the analyzing speed of traditional analyzing method is low, there is a long way behind needs of production. On the condition of poor quality coal and wide fluctuation, not only is the furnace operation rate low but also the phenomenon like stop working and flameout is always appeared. All these conditions heavily influenced the safe and economic operation of thermal power plant. Through on-line measuring device for material elements, the coal quality can be accurately known, which is convenient for workers to adapt fire timely, so as to ensure safe and steady operation of unit. So the on-line measuring device for material elements is of very significant importance for safe and economic production of processing style industries.

Operation principle
The on-line measuring device for material elements adopts neutron induced prompt γray analysis (NIPGA), which is based on the neutron capture (N, γ) reaction and fast neutron non-elastic scattering (n, n' γ)reaction, realizes the online measuring of main material elements. The reaction between high energy neutron and nuclide in coal produces prompt γray corresponding with nuclide characteristics. Through verifying energy of signatureγray to recognize corresponding nuclide, and through the quantity to analysis the content of nuclide.

Functions
1. Directly verify contents of all elements in coal, including C, H, O, N, S, Al, Si, Fe, Ca, etc. Meanwhile, it can verify trace elements like Ti, Na, K in coal.
2. Provide industrial analytical data of coal, including calorific power, volatile, ash, moisture and fixed carbon.
3. Provide combustion characteristic of coal, including ash fusing point and agglomerating index.

Device composition
The on-line measuring device for material elements mainly consists of tracking and protection system, spectral analysis and control system and processing system of computer. The detector is set on coal conveying belt. The coal flows on the belt is exposed to the source to radiate theγray, and the BGO detector receives theγray and convert it into and light signal, which is transmitted to the energy analysis unit for analysis, then, convert into nuclide and content. Through industrial content changing unit and material characteristics analysis system, material characteristics can be detected.