Flotation separation of quartz from magnesite using carboxymethyl cellulose as depressant

Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.

First application of large reactivity measurement through rod drop based on three-dimensional space–time dynamics

Abstract Reactivity measurement is an essential part of a zero-power physics test,which is critical to reactor design and development.The rod drop experimental technique is used to measure the control rod worth in a zero-power physics test.The conventional rod drop experimental technique is limited by the spatial effect and the difference between the calculated static reactivity and measured dynamic reactivity;thus,the method must be improved.In this study,a modified rod drop experimental technique that constrains the detector neutron flux shape function based on three-dimensional space–time dynamics to reduce the reactivity perturbation and a new method for calculating the detector neutron flux shape function are proposed.Correction factors were determined using Monte Carlo N-particle transport code and transient analysis code for a pressurized water reactor at the Ulsan National Institute of Science and Technology and Xi’an Jiaotong University,and a large reactivity of over 2000 pcm was measured using the modified technique.This research evaluated the modified technique accuracy,studied the influence of the correction factors on the modification,and investigated the effect of constraining the shape function on the reactivity perturbation reduction caused by the difference between the calculated neutron flux and true value,using the new method to calculate the shape function of the detector neutron flux and avoiding the neutron detector response function(weighting factor)calculation.