The Method And Instrument Of Automatic Determination Of Modulus Of Sodium Silicate Based On Potentiometric Titration Technology

The sodium silicate binder possess many advantages including being odor free, non-toxic and environmental friendly, hence it is widely applied in foundry molding sand, chemistry painting, papermaking and many other industries. The most important parameter to measure sodium silicate binder properties is modulus, sodium silicate binder has strict requirements on modules in different applied; therefore determination of modulus of sodium silicate accurately is very important. The existing determination of modulus methods mostly use indicator to determinate end-point, and operated in a manual way, so the testing cycle is long and the accuracy is not high. According to deficiencies of existing methods, this paper applied potentiometric titration technology in determination of modulus of sodium silicate, and put forward a new method and instrument of automatic determination of modulus of sodium silicate.This paper introduced the principle and the existing methods to determinate modulus of sodium silicate, based on the analysis and summerize between domestic and international research, adopted the principle of determination of modulus as the foundation, as well as the introduction of advanced potentiometric titration technology, put forward a new method of automatic determination of modulus of sodium silicate based on potentiometric titration technology. This method used potential signal acquisited by pH electrode instead of human eye to determinate end-point; used micro peristaltic pump to replace manually add and titrate; used magnetic heating and stirring device to heat and mix solution; microcontroller completed data processing and controlled the whole titration process. On the basis of this method, this paper developed an instrument which can determinate modulus of sodium silicate automatically, fleety and accurately.As for the part of hardware design, this paper expounded the system structure and principle of the instrument; detailly intruduced the overall hardware solution, the composition of the hardware and the selection of the hardware modules; and with STM32F103 chips as the core, completed the instrument peripheral expansion circuit.As for the part of software design, this paper selected keil MKD as software development platform; according to the requirement of instrument, divided the functions of software, and developed the main determination process, calibration process, etc; on this basis, according to the software design specification, used C language to achieve software development of instrument.The experiments show that this instrument can well solve issues in the traditional way, such as the testing cycle is long, efficiency is low, and the accuracy is not high, etc; and reduce labour intensity. This instrument can also be used to determinate residual Na₂O content in used sodium silicate sand or recycled sodium silicate sand.