Experimental Study on Application of Boron Mud Secondary Resource to Oxidized Pellets Production

In order to realize comprehensive and massive treatment of boron mud secondary resource, fundamental study on boron mud applied to oxidized pellets production as additive was carried out in the paper under laboratory conditions. The effects of boron mud on the performance of oxidized pellets were investigated systemically, and boron mud was combined with other boron-rich material innovatively. The results showed that, within certain limits, boron mud can improve properties of oxidized pellets. The bentonite content decreased to 0.3 % when adding 1.0 % boron mud additive and the pellets met blast furnace requirements. With the combination additive content 0.8 %, bentonite content can be further decreased to 0.2 %, and the pellets properties were better than base pellet. Therefore, it was an effective way to reduce environmental pollution and optimize blast furnace operation by developing boron mud secondary resource as pellets additive.

Study on Extraction of Mg from Boron Mud

Mg was extracted from boron mud through calcining method. The technological process is that the boron mud was calcined at 700 °C for 3 h then uniformly mixed with (NH4)2SO4in proportion and calcined. The reaction process was studied by TG-DTA and XRD, which is that MgO in calcined boron mud reacts with (NH4)2SO4to produce (NH4)2Mg2(SO4)3at low temperature, then with increasing the temperature, (NH4)2Mg2(SO4)3decomposes into MgSO4. The effects of calcination temperature, mol ratio of reaction substrates and calcination time on conversion rate of Mg were studied. The results indicate that the conversion rate of Mg increases with the increasing of calcination temperature first then decreases, increases with the increasing of calcination time and mol ratio of (NH4)2SO4and MgO. When the calcination temperature is 500 °C, the calcination time is 3 h, the mol ratio of (NH4)2SO4and MgO is 0.9:1, the conversion rate of Mg is 81.9 %.

Study on the Phase Composition and Particle Size of Boron Mud

The phase composition and particle size of the boron mud is investigated by X-ray diffractometry (XRD), scanning electron microscope (SEM) and laser particle size analyzer. The mainly phase composition of the boron mud are magnesite (MgCO3) and forsterite (Mg2SiO4). The mainly phase composition of the calcined boron mud are forsterite (Mg2SiO4) and a small amount magnesia (MgO). the sizes of the boron mud are about 2~6μm and a few of them are bigger and less than 10μm and the particle size of less than 10μm is about 60%.