招远市金矿资源开发利用调查评价研究

为深入贯彻生态文明思想，促进矿产资源全面节约和高效利用，对招远市展开了金矿矿产资源开发利用水平调查评价，对2018年度数据进行整理和实地核查后，进行了单个矿山评价和多矿山评价，包括矿种评价、地区评价、行业评价。招远市16个矿山实际数据和基准值指标对比显示，单个矿山评价和多矿山评价的达标率均为100%。在此基础上，分析了金矿矿产资源资源开发利用水平调查评价的意义和存在问题。     

Synthesis and characterization of calcium aluminate compounds from gehlenite by high-temperature solid-state reaction

The mineral transition mechanism and self-pulverization property of the sintered products in the Ca₂Al₂SiO₇-CaO system were systematically studied using pre-synthesized gehlenite determined by XRD, SEM, FTIR and particle size analyses. The minerals of Ca₁₂Al₁₄O₃₃, CaAl₂O₄, Ca₃SiO₅ and Ca₂SiO₄ are formed by the direct reactions of Ca₂Al₂SiO₇ with CaO. CaAl₂O₄ reacts with CaO to form Ca₁₂Al₁₄O₃₃ or Ca₃Al₂O₆, while Ca₃SiO₅ reacts with Ca₂Al₂SiO₇ to form Ca₂SiO₄ and calcium aluminate compounds. The sintered products mainly contain CaAl₂O₄, Ca₁₂Al₁₄O₃₃ and Ca₂SiO₄ at 1350?°C or above 1500?°C when the molar ratio of CaO to Al₂O₃ is 1.0. Increasing the sintering duration or the CaO consumption promotes the transition of Ca₂Al₂SiO₇ to Ca₂SiO₄ and calcium aluminate compounds when sintered at 1350?°C, which accordingly improves the self-pulverization property of the sintered products. The formed minerals of Ca₁₂Al₁₄O₃₃, CaAl₂O₄ and Ca₂SiO₄ transform into Ca₂Al₂SiO₇ again when the sintering temperature is between 1400?°C and 1450?°C, and the corresponding self-pulverization property of the sintered products deteriorates sharply.     

Influence of Alkaline Additives and Buffers on Mineral Trapping of CO2 under Mild Conditions

Carbon dioxide (CO₂) gas is the main contributor to climate change. CO₂ storage in underground brines and oil‐field brines by mineral trapping has been considered as a promising alternative in order to reduce CO₂ emissions. However, permanent storage of CO₂ in stable carbonate minerals is greatly dependent on brine pH, being favored over an alkaline pH. The effect of alkaline additives (NaOH, KOH, CaO) and buffer solutions (NaHCO₃/NaOH, Na₂HPO₄/NaOH, NH₄Cl/NH₄OH) on the mineral trapping of CO₂ under mild conditions using a synthetic brine is investigated. The results indicate that both NaOH+NH₄Cl/NH₄OH and KOH+NH₄Cl/NH₄OH mixtures promote precipitation mainly of calcium carbonate (CaCO₃).     

CO2 sequestration by magnesite mineralisation through interaction of Mg-brine and CO2: integrated laboratory experiments and computerised geochemical modelling

ABSTRACT

Several Carbon Capture and Storage (CCS) techniques have been studied including injections of carbon dioxide (CO₂) into the mature and/or depleted hydrocarbon reservoirs and deep saline aquifers. This work aims to test storing CO₂ into the magnesium-rich evaporite strata and also into the stratigraphic intervals containing Mg-rich brines. The test simulates Mg-carbonation of the synthetic solution obtained from the Mg-evaporite mineral, bischofite – both experimentally in the laboratory condition and also through computerised geochemical simulation. The laboratory experiments, which resulted in the crystallisation of anhydrous magnesite, were analysed. The TOUGHREACT^TM, Geochemist’s Workbench^TM (GWB) and PHREEQC^TM software simulated the experiments as computerised geochemical model and tested the results for natural geological conditions. The geochemical simulations successfully demonstrate the immense CCS potential for the Mg-evaporite (as well as the sedimentary strata charged with Mg-evaporitic brine) at their subsurface geological occurrences at elevated pressure-temperature and high salinity.     

飞行时间二次离子质谱对矿物表面性质的研究

随着易选矿石的逐步枯竭,低品位、嵌布粒度细等难选矿石的开发利用已成必然趋势。目前,矿物加工已经从实践生产阶段发展到了理论研究指导实践生产的阶段,因此具有分辨率高、信息量大、灵敏快速以及样品用量少等特点的矿物表层研究方法来支撑理论研究是必不可少的。飞行时间二次离子质谱法(TOF-SIMS)是近年来在矿物加工中使用较多的一种矿物表面化学分析方法,具有表面质谱、化学成像、深度剖析、快速灵敏及数据精准的优点,因此总结归纳了近年来TOF-SIMS在矿物加工中应用取得的成果,以期为学者提供可靠的理论依据及技术支持。     

Integrated planning and scheduling under production uncertainties: Bi-level model formulation and hybrid solution method

We propose a novel method for integrating planning and scheduling problems under production uncertainties. The integrated problem is formulated into a bi-level program. The planning problem is solved in the upper level, while the scheduling problems in the planning periods are solved under uncertainties in the lower level. The planning and scheduling problems are linked via service level constraints. To solve the integrated problem, a hybrid method is developed, which iterates between a mixed-integer linear programming solver for the planning problem and an agent-based reactive scheduling method. If the service level constraints are not met, a cutting plane constraint is generated by the agent-based scheduling method and appended to the planning problem which is solved to determine new production quantities. The hybrid method returns an optimality gap for validating the solution quality. The proposed method is demonstrated by two complicated problems which are solved efficiently with small gaps less than 1%.     

Multiobjective optimization and decision-making for DG planning considering benefits between distribution company and DGs owner

Environmental concerns and fossil fuels uncertainties have resulted in promotion of multi-source and multi-type distributed generation (DG). However, the development of DG has brought new challenges to distribution system. This paper proposes a multiobjective optimization and decision-making methodology for determining size and site of multi-source and multi-type DG in distribution networks. The proposed method is based on the combination of analytical method and multi-objective optimization method and set pair of analysis (SPA). The comprehensive analysis of the loss sensitivity factor, voltage profile and reliability gave DG candidate locations. The multi-objective optimization method is based on an already-known but suitably modified Non-Dominated Sorting Genetic Algorithm (NSGA) to solve the constructed formulations, which include maximizing benefits of DG owner and Distribution Companies (DisCo) while meeting some constraints. The objective not only includes costs for DG investment, DG operation and maintenance, purchase of power by DisCo but also involving quantization for improvement of losses, voltage, reliability, etc. SPA, which is a multi-attribute decision analysis, is applied to obtain the synthetic priority of pareto solutions and carry out rank stability analysis. Furthermore, the proposed technique is applied to 37-bus distribution network. The results show that the proposed method is fast, reliable and available to determine size and site of DG as well as balance benefits between DG owner and DisCo.     

In-situ measurement of mineral phase transition and kinetics in roasting process of Bayan Obo mixed rare earth concentrate by sodium carbonate

In this study, the Bayan Obo rare earth concentrates mixed with Na₂CO₃ were used for roasting research. The phase change process of each firing stage was analyzed. The kinetic mechanism model of the continuous heating process was calculated. This study aims to recover valuable elements and optimize the production process to provide a certain theoretical basis. Using X-ray diffraction (XRD), Fourier infrared spectroscopy, scanning electron microscopy with energy dispersive spectrometry, the reaction process and the existence of mineral phases were analyzed. The variable temperature XRD and thermogravimetric method were used to calculate the roasting kinetics. The phase transition results show that carbonate-like substances first decompose into fine mineral particles, and CaO, MgO, and SiO₂ react to form silicates, causing hardening. Further, REPO₄ and NaF can directly generate CeF₃ and CeF₄ at high temperatures, and a part of CeF₄ and NaF forms a solid solution substance Na₃CeF₇. Rare earth oxides calcined at a high temperature of 750 °C were separated to produce Ce_0.6Nd_0.4O_1.8, Ce₄O₇, and LaPrO_3+x. Then, BaSO₄, Na₂CO₃, and Fe₂O₃ react to form barium ferrite BaFe₁₂O₁₉; the kinetic calculation results show that during the continuous heating process, the apparent activation energy E reaches the minimum in the entire reaction stage in the temperature range of 440–524 °C, and the reaction order n reaches the maximum, which indicates that the decomposition product REFO significantly impacts the reaction system and reduces the activation energy. The mechanism function is F(α) = [?ln (1?α)]^1/3. The reaction order n reaches the minimum in the temperature range of 680–757 °C, and the apparent activation energy E is large. The difficulty of the reaction increases during the final stage. The reaction mechanism function is F(α) = [1?(1?α)^1/3]². Observing the entire reaction stage, the step of controlling the reaction rate changes from random nucleation to three-dimensional diffusion (spherical symmetry).     

Effect of CaO mineral change on coal ash melting characteristics

The change of mineral composition in ash and the effect of CaO on the melting characteristics of coal ash were studied by adding different contents of CaO to coal ash. At the same time, the Factsage thermodynamics software was used to simulate the mineral changes in the synthetic ash to support and verify the experimental results. The results show that with the increase of CaO content, the melting characteristic temperature of coal ash first decreases and then rises. After adding a certain amount of CaO, the quartz with higher melting point completely disappears, and the melting point of the coal ash reaches a minimum value. And with the increase of CaO content, the appearance of wollastonite and single crystal calcium oxide mineral makes the melting point of coal ash gradually increase. It can be seen from the phase diagram calculated by Factsage that as the CaO content increases, the corresponding position of the coal ash gradually moves from the hematite region to the calcareous region. And the phenomenon of low temperature eutectic occurs when the CaO content is 35%, which is consistent with the trend of temperature change of the melting characteristics. These phenomena all indicate that the change in the melting point of coal ash is nonlinear as the content of CaO minerals increases.