Xian Jun Lu

Alkali Activation of Granulated Blast Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

Study on Adsorption Properties of Different Dyes on Montmorillonite

Using Octadecyltrimethylammonium cations with long carbon chain to modify calcium montmorillonite samples, the adsorption properties of different dyes on montmorillonite before and after modification were investigated. Results showed that the basic dye of methylene blue was easily adsorbed by natual calcium montmorillonite, while the adsorption ability for acid blue and neutral blue was greatly improved when it was organically modified, and the adsorption amount increased with the increasing of modifier dosage. The adsorption ratio was influnced by reaction time, the temperature and the solution’s pH value. It suggested that the adsorption balance time was about 60min; higher temperature was good for acid blue adsorbed on organic montmorillonite, but neutral blue’s adsorption amount was greater at the room temperature; the optimum pH was 9 for methylene blue adsorption, while low pH was better for acid blue and neutral blue adsorption.

Chemical Activation of Cementing Properties of Granulated Blast Furnace Slags

Using CaO, NaOH and Na2CO3 as activators, the effects of dosage and combination of the activators on the cementing property of granulated blast furnace slags were investigated, and the hydration products of the activated slags were detected by X-ray powder diffraction (XRD) analysis. Results indicate that CaO can be used as an effective activator for the slag samples and its optimum dosage is about 10%, but the CaO activated slags shows much lower early strength than the Portland cement. However, the early strength of the CaO activated slag can be remarkably improved by the addition of NaOH or Na2CO3. Under the addition of about 6% NaOH or Na2CO3, the overall compressive strength of the alkali activated slag is higher than a 42.5MPa Portland cement. XRD analysis revealed that the hydration products of the alkali activated slags are mainly amorphous materials, which is quite different from that of the Portland cement.

Study on Porous Structure and Surface Characteristics of Al-Pillared Montmorillonite

Al-pillared montmorillonite (Al-PILM) prepared with Keggin ions was studied by means of XRD, SEM-EDS and N2 adsorption-desorption isotherms.The rusults show that, compared to unpillared Na-montmorillonite (Na-M), the interlayer spacing d(001) value, BET specific surface area, surface fractal dimension and the proportion of microporous specific surface area of Al-PILM are larger and the surface is relatively rough. The BJH porous volume distribution of Al-PILM is the most probable distribution, and the most probable pore size is about 2 nm, belonging to mesopore. The porous structure of Al-PILM is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. Besides, the results of elemental distribution show that the ions exchange action between Na+ and hydroxy-Al cations in pillaring solution occurs in the formation of Al-PILM.

Research on Preparation and Properties of Backfilling Cementation Material Based on Blast Furnace Slag

The blast-furnace slag (BFS) has been characterized by chemical and phase composition to evaluate its hydration reactivity. It has high potential activity for its glassy structure, so its use to prepare new filling cementation material is possible. New backfilling cementation material composition has been formulated and optimized by activation of BFS. The optimal formula of new backfilling cementation material SL(Slag activated by lime) and SLG(Slag activated by lime and desulfurization gypsume) was 87% BFS ,13% lime and 78.4% BFS, 11.8% lime, 9.8% desulfurization gypsume respectively. Finally, the feature of cementation properties was analyzed through comparison between new cementation material and ordinary Portland cement with compressive strength, water requirement of normal consistence, setting time, bleeding water and slump. The result showed that material SL and SLG have superior performance to ordinary Portland cement used to mining cemented filling.

Study on Microstructure Variation Laws of Al-Pillared Montmorillonite

Al3+/clay ratio is one of the important factors influencing microstructure of Al-pillared montmorillonite. Microstructure variation laws of Al-pillared montmorillonite prepared under the condition of different Al3+/clay ratio are systematically studied by XRD, FTIR, specific surface area and pore size analysis. The results show that the interlayer spacing and BET specific surface area of Al-pillared montmorillonite are remarkably affected by the Al3+/clay ratio. The interlayer spacing d(001) value and BET specific surface area of Al-pillared montmorillonite increase firstly and then decrease with the increases of the Al3+/clay ratio, and they reach to maximum when the Al3+/clay ratio is 10mmol/g. Besides, the BJH porous volume distribution of Al-pillared montmorillonite is the most probable distribution, and the most probable pore size is about 2 nm, which is attributed to mesopore. The porous structure of hydroxy-Al pillared montmorillonite is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. With the increase of the Al3+/clay ratio, BJH total porous volume and mesoporous volume of hydroxy-Al pillared montmorillonite decreases, while the proportion of microporous volume in the total porous volume increases. The proportion of microporous specific surface area of all the hydroxy-Al pillared montmorillonite samples is about 62% and is much larger than that of Na-M and those of mesopore and macropore, indicating the main action of intercalation of hydroxy-Al pillaring solution into montmorillonite interlayer is to increase the micropore amount.

Research on Properties and Reaction Mechanism of Blast Furnace Slag Backfilling Cementing Material

According to XRD, DTA and SEM detections, the hydration products of blast furnace slag based cementing material SL, SLG. were studied in different age periods. The XRD analysis of cementing material SL hydration products showed the composition of hydration products were mainly amorphous substances, few crystalline substances. Characteristic peak of ettringite, such as AFt, hadn’t been found in the spectral line of DTA, and it hadn’t been found in the figures of SEM, either, which was accordant with the conclusion that the cementing performance of SL mainly coming from gel of hydrated calcium silicate (CSH) and hydrated calcium aluminate. But the cementing performance of SLG mainly coming from Aft, CSH and AFm from hydration products analysis of different age periods.

Preconcentration Research on Mineral Processing for a Extremely Lean Iron Ore in Inner Mongolia

The results show that under the condition of grinding fineness(-200 mesh content) of 52.88% and magnetic field intensity of 0.2T, the index of concentrate yield is 13.25%, concentrate grade is 58.75% and concentrate recovery is 57.32% with preconcentration technology by magnetic separation.

Research on Cementing Performances of Environment-Friendly Backfilling Cementation Material Based on Blast Furnace Slag

The blast-furnace slag （BFS）has been characterized by chemical and phase composition to evaluate its hydration reactivity. It has high potential activity for its glassy structure, so its use to prepare new filling cementation material is possible. New backfilling cementation material composition has been formulated and optimized by activation of BFS. The optimal formula of new backfilling cementation material SL(Slag activated by lime) and SLC(Slag activated by lime and calcium chloride) was 87% BFS ,13% lime and 86.84% BFS, 13.02% lime, 0.14% calcium chloride respectively. Finally, the feature of cementing properties was analyzed through comparison between new cementation material and ordinary Portland cement with compressive strength, water requirement of normal consistence, setting time, bleeding water and slump. The result showed that material SL and SLC have superior performance to ordinary Portland cement used to mining cemented filling.

Advances in Research on Adsorption Characteristics of Alkylammonium in Montmorillonite Inter-Layer Space

Adsorption Characteristics and controlling methods of long-chain alkyl ammonium cations in montmorillonite interlayer space are theoretic evidence of the montmorillonite/alkylammonium complexes in the process of preparation. This paper summarizes the advances in research on adsorption characteristics of alkyl ammonium in montmorillonite inter-layer space.