The massive accumulation of flue gas desulfurization (FGD) gypsum produced in the wet limestone-gypsum flue gas desulfurization process not only encroaches on lands but also causes serious environmental pollution. The preparation of α-hemihydrate gypsum (α-HH) is an important way to achieve high-value utilization of FGD gypsum. Although the glycerol-water solution approach can be used to produce α-HH from FGD gypsum under mild conditions, the transition is kinetically unfavorable in the mixed solution. Here, an easy pretreatment was used to activate FGD gypsum by calcination and hydration to readily complete the transition. The pretreatment deteriorated the crystallinity of FGD gypsum and caused it to form small irregular flaky crystals, which dramatically increased the specific surface area. Additionally, most of the organics adsorbed onto FGD gypsum surfaces were removed after pretreatment. The poor crystallinity, increased specific surface area, and elimination of organics adsorbed onto crystal surfaces effectively improved the conversion activity of FGD gypsum, thereby promoting dihydrate gypsum (DH) dissolution and α-HH nucleation. Overall, the phase transition of FGD gypsum to α-HH is facilitated.

The coal with low moisture during carbonization could not only increase the yield of coke, but also promote the coke quality and reduce the energy consumption. In this paper, the influence of the moisture in the blend coal (1.8%–10.13%) on the product yields and coke quality during coal carbonization were investigated. The results show that the coke yield is increased from 75.90% to 77.16%, and the coke qualities such as coke strength after reaction with CO₂ (CSR), coke reactivity index (CRI), fragmentation index (M25) and abrasion index (M10)) are also improved when the moisture of the blend coal decreases from 10.13% to 1.80 % in a bench scale reactor. Due to the secondary reaction, tar become lighter when the moisture is decreased. In order to further prove the above results, the blend coal with 1.8% and 9%–10% (common moisture used in coke plant) moisture is carbonized in a coke oven with 6 m height, the results show that CRI are 23.4% and 27.3%, CRS are 67.1% and 62.2% under 1.8% and 9%–10% moisture of blend coal. Moreover, the variation of the moisture in blend coal has a limited influence on dust emission at the ascension pipe and the charging car.

As a main charging burden of blast furnace (BF) ironmaking process, pellets play an important role in ironmaking process. However, compared with sinters, there are some inevitable disadvantages for traditional acid pellets, e.g., reduction swell, low melting temperature. Therefore, the fluxed-pellets have been applied in BF, especially MgO-fluxed pellets. In the present study, the effects of category and content of MgO bearing additive on the compressive strength (CS), reduction swelling index (RSI), reduction disintegration index (RDI) and melting-dripping properties of the pellets were investigated. Minerals composition, pore distribution and microstructure of MgO-flux pellets were studied by X-ray powder diffraction (XRD), mercury intrusion method and scanning electron microscopy (SEM), respectively. The results show that the light burned magnesite (LBM) is more suitable MgO bearing additive for fluxed-pellets. With increasing LBM content from 0 to 2.0%, the CS decreases from 3066 to 2689 N, RSI decreases from 16.43% to 9.97% and RDI decreases from 19.2% to 12.99%. The most appropriate MgO bearing additive content in the fluxed- pellets is 2.0% according to principal component analysis (PCA).

The Changsha-Xiangtan-Zhuzhou City Group is a heavy industrial district and accepted as the serious pollution area in the Xiangjiang River basin. In this study, 7 metals (Pb, Hg, Cd, As, Zn, Cu and Se) and the river water quality parameters including pH, dissolved oxygen (DO), Escherichia coli (E. coli), potassium permanganate index (COD_Mn), dichromate oxidizability (COD_Cr), five-day biochemical oxygen demand (BOD₅), ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), total phosphorus (TP) and fluoride (F⁻) in 18 sampling sites of the Changsha-Xiangtan-Zhuzhou section are monthly monitored in 2016, which is the year to step into the second stage of the “Xiangjiang River Heavy Metal Pollution Control Implementation Plan”. It is found that E. coli, TN and TP are the main pollutants in the Changsha-Zhuzhou-Xiangtan section, and the pollution of heavy metal is not serious but As with potential risk to local people especially children should be concerned. In addition, Xiangtan city is mainly featured with heavy metal pollution, while Zhuzhou and Changsha city are both featured with other pollutants from municipal domestic sewage.

Zirconia has been used in medical applications since last few years and an optimum and cost-effective condition in grinding zirconia has drawn industrial attention. This paper aimed to improve and control the surface integrity, flexural strength and grinding cost in grinding partially stabilized zirconia (PSZ) using a diamond grinding wheel. The phase transition and grindability of PSZ were also evaluated. Ground surfaces analysis shows that all samples subjected to the grinding presented an increase in surface integrity, and the subsurface damages 100 below the surface were reduced from 3.4% to 0.9%. The flexural strength using 3 point bending test (3PB) shows that grinding increased the flexural strength more than 29% which is the result of higher surface integrity. The ground surfaces were analyzed using X-ray diffraction (XRD) and the results shows that T-M phase transition trend is in accordance with the surface integrity. In other words, XRD analyses prove that T-M phase transition results in higher flexural strength and surface integrity. It was also observed that in the best condition, the grinding cost was reduced by 72%. It can be concluded that controlling the grinding condition in grinding PSZ will result in the increase of the surface integrity and flexural strength. A mathematical model was created to find an optimum condition using response surface method (RSM). It is observed that feed rate has greater effect on the outputs rather than depth of cut.

The multiple cracking and deflection hardening performance of polyvinyl alcohol fiber reinforced engineered cementitious composites (PVA-ECC) under four-point flexural loading have been investigated. Matrices with different binder combinations and W/B ratios (from 0.44 to 0.78) providing satisfactory PVA fiber dispersion were specially designed. Effect of pre-existing flaw size distribution modification on deflection hardening behavior was comparatively studied by adding 3 mm diameter polyethylene beads into the mixtures (6% by total volume). Natural flaw size distributions of composites without beads were determined by cross sectional analysis. The crack number and crack width distributions of specimens after flexural loading were characterized and the possible causes of changes in multiple cracking and deflection hardening behavior by flaw size distribution modification were discussed. Promising results from the view point of deflection hardening behavior were obtained from metakaolin incorporated and flaw size distribution modified PVA-ECCs prepared with W/B=0.53. The dual roles of W/B ratio and superplasticizer content on flaw size distribution, cracking potential and fiber-matrix bond behavior were evaluated. Flaw size distribution modification is found beneficial in terms of ductility improvement at an optimized W/B ratio.

Al₂O₃ ceramic powder was applied to modify the large pores defects on the surface of the porous metal Ti support, in situ oxidation method was a convenient method to prepare defect free ceramic/Ti composite membranes on this basis. In situ oxidation conditions experimental results show that the best condition for preparing the TiO₂-Al₂O₃/Ti composite membrane is under 800 °C for 2 h, and the microstructure and pore sizes of the TiO₂-Al₂O₃/Ti composite membranes are affected obviously. The thickness and composition of the TiO₂/Ti composite membranes are determined by SEM and XRD completely. The pore size distribution of the composite membrane is measured by bubble pressure method, the most probable aperture is about 3.12 µm, while the average pore size of defect free TiO₂-Al₂O₃/Ti is about 3.23 µm. After ultrasonic treatment, the slight weight change of membranes reveals no observable change, which indicates that TiO₂-Al₂O₃/Ti composite membranes maintain a good stability.

A two-pass annealing/quenching internal spinning process with small-end rotations is proposed to form a curved generatrix conical thin-walled shell. That is, annealing at 360°C for 2 h followed by the 1st pass spinning, and finally quenching in ice water after holding for 1 h at 498 °C followed by the 2nd pass spinning. ABAQUS finite element software is used to simulate the internal spinning process of the products formed under different forming parameters. The distribution laws of spinning force, the stress and strain under different forming processes were compared and analyzed. The mechanical properties and microstructure of the products are subsequently analyzed. The results show that the strain and the residual stress in the skin area of the formed products under two-pass spinning process more uniform, and the hardness and the mechanical performance are improved. The microstructure of the products formed with the 0.15 mm thickness reduction at the 2nd pass is excellent. And the second phase grain size distributed uniformly in the range of 3–6 µm. Whereas, the second phase particles are broken seriously and the size distribution inhomogeneity is increased when the thickness reduction in the skin area is greater than 0.20 mm at the 2nd pass spinning process.

5G baseband signal processing places greater real-time and reliability requirements on hardware. Based on the architecture of the MaPU, a reconfigurable computing architecture is proposed according to the characteristics of the 5G baseband signal processing. A dedicated instruction set for 5G baseband signal processing is proposed. The corresponding functional units are designed for reuse of hardware resources. A redirected register file is proposed to address latency and power consumption issues in internetwork. A two-dimensional code compression scheme is proposed for cases in which the use ratio of instruction memory is low. The access mode of the data memory is extended, the performance is improved and the power consumption is reduced. The throughput of 5G baseband processing algorithm is one to two orders of magnitude higher than that of the TMS320C6670 with less power consumption. The silicon area evaluated by layout is 5.8 mm², which is 1/6 of the MaPU’s. The average power consumption is 0.7 W, which is 1/5 of the MaPU’s.

Designing optimal time and spatial difference step size is the key technology for quantum-random filtering (QSF) to realize time-varying frequency periodic signal filtering. In this paper, it was proposed to use the short-time Fourier transform (STFT) to dynamically estimate the signal to noise ratio (SNR) and relative frequency of the input time-varying frequency periodic signal. Then the model of time and space difference step size and signal to noise ratio (SNR) and relative frequency of quantum random filter is established by least square method. Finally, the parameters of the quantum filter can be determined step by step by analyzing the characteristics of the actual signal. The simulation results of single-frequency signal and frequency time-varying signal show that the proposed method can quickly and accurately design the optimal filter parameters based on the characteristics of the input signal, and achieve significant filtering effects.

Direct online measurement on product quality of industrial processes is difficult to be realized, which leads to a large number of unlabeled samples in modeling data. Therefore, it needs to employ semi-supervised learning (SSL) method to establish the soft sensor model of product quality. Considering the slow time-varying characteristic of industrial processes, the model parameters should be updated smoothly. According to this characteristic, this paper proposes an online adaptive semi-supervised learning algorithm based on random vector functional link network (RVFLN), denoted as OAS-RVFLN. By introducing a L₂-fusion term that can be seen a weight deviation constraint, the proposed algorithm unifies the offline and online learning, and achieves smoothness of model parameter update. Empirical evaluations both on benchmark testing functions and datasets reveal that the proposed OAS-RVFLN can outperform the conventional methods in learning speed and accuracy. Finally, the OAS-RVFLN is applied to the coal dense medium separation process in coal industry to estimate the ash content of coal product, which further verifies its effectiveness and potential of industrial application.

Remote control process system with distributed time-delay has attracted much attention in different fields. In this paper, non-linear remote control of a single tank process system with wireless network is considered. To deal with the distributed time-delay in a large-scale plant, the time-delay compensation controller based on DCS devices is designed by using operator theory and particle filter. Distributed control system (DCS) device is developed to monitor and control from the central monitoring room to each process. The particle filter is a probabilistic method to estimate unobservable information from observable information. First, remote control system and experimental equipment are introduced. Second, control system based on an operator theory is designed. Then, process system with distributed time-delay using particle filter is carried out. Finally, the actual experiment is conducted by using the proposed time-delay compensation controller. When estimating with the proposed method, the result is close to the case in which the distributed time-delay does not exist. The effectiveness of the proposed control system is confirmed by experiment results.

Microbial fuel cell (MFC) is a kind of promising clean power supply energy equipment, but serious nonlinearities and disturbances exist when the MFC runs, and it is an important topic to guarantee that the output voltage reaches the setting value quickly and smoothly. Regulating the feeding flow is an effective way to achieve this goal, and especially, the satisfactory results can be achieved by regulating anode feeding flow. In this work, a feedforward fuzzy logic PID algorithm is proposed. The fuzzy logic system is introduced to deal with the non-linear dynamics of MFC, and corresponding PID parameters are calculated according to defuzzification. The magnitude value of the current density is used to simulate the value of the external load. The simulation results indicate that the MFC output voltage can track the setting value quickly and smoothly with the proposed feedforward fuzzy logic PID algorithm. The proposed algorithm is more efficient and robust with respect to anti-disturbance performance and tracking accuracy than other three control methods.

Organic Rankine cycle (ORC) is widely used for the low grade geothermal power generation. However, a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator. The condensing temperature, cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience. In order to optimize the ORC system comprehensively, the coupling effect of evaporation and condensation process was proposed in this paper. Based on the laws of thermodynamics, the energy analysis, exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power, thermal efficiency, exergy efficiency, thermal conductivity, irreversible loss, etc., using geothermal water at a temperature of 120 °C as the heat source and isobutane as the working fluid. The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance. The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature, but the system comprehensive performance corresponds to a lower condensing temperature than the net power output.

In the travel process of urban residents, travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes, which affects their following trips. This process can be seen as a repeated game between members of the travelers. Based on the analysis of this game and its evolution trend, a multi-dimensional game model of low-carbon travel for residents is established. The two dimensional game strategies include whether to accept the low-carbon concept and whether to choose low-carbon travel. Combined with evolutionary game theory, the low-carbon travel choices of residents in different cities are simulated, and the evolutionary stability strategies are obtained. Finally, the influences of the main parameters of the model on the evolution process and stability strategies are discussed. The results show that travelers would develop towards two trends. Cities with more developed public traffic system have a higher proportion of receiving low-carbon concept and choosing low-carbon travel. Cities with underdeveloped public transport system could increase this proportion by some measures such as encouraging residents to choose slow transport and increasing the propaganda of low-carbon travel, but the positive effects of the measures like propaganda have a limited impact on the proportion.

For the investigation of mechanical properties of the bimrocks with high rock block proportion, a series of laboratory experiments, including resonance frequency and uniaxial compressive tests, are conducted on the 64 fabricated bimrocks specimens. The results demonstrate that dynamic elastic modulus is strongly correlated with the uniaxial compressive strength, elastic modulus and block proportions of the bimrocks. In addition, the density of the bimrocks has a good correlation with the mechanical properties of cases with varying block proportions. Thus, three crucial indices (including matrix strength) are used as basic input parameters for the prediction of the mechanical properties of the bimrocks. Other than adopting the traditional simple regression and multi-regression analyses, a new prediction model based on the optimized general regression neural network (GRNN) algorithm is proposed. Note that, the performance of the multi-regression prediction model is better than that of the simple regression model, owing to the consideration of various influencing factors. However, the comparison between model predictions indicates that the optimized GRNN model performs better than the multi-regression model does. Model validation and verification based on fabricated data and experimental data from the literature are performed to verify the predictability and applicability of the proposed optimized GRNN model.

The performance of magnesium oxychloride cement concrete (MOCC) in road engineering in the arid region in northwest China was investigated over a two-year period. Two categories of MOCC pavement, light-burnt magnesia concrete road (Road-L) and dolomite concrete road (Road-D), were prepared with light-burnt magnesia and a mixture of light-burnt magnesia and caustic dolomite (1:3 by mass), respectively. Variations in the properties of the MOCC pavement, such as compressive and flexural strength, mineralogical phase, and microstructure, after being exposed to two rainy seasons in the field were monitored. The compressive strength of the cored samples were conducted after being aged for 28 d, and the compressive and flexural strength were tested at ages of 1, 2, 3, 28, 90, 180, 270, 360 and 720 d. The mineralogical phase and microstructure of the pavement were also analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results demonstrate that MOCC pavement obtained desirable compressive and flexural strengths after curing for 3 d for Road-L and 28 d for Road-D. Both of the compressive and flexural strength of Road-L and Road-D decreased slightly after experiencing two rainy seasons, with the major hydration products being 5Mg(OH)₂·MgCl₂·8H₂O (Phase 5) and 3Mg(OH)₂·MgCl₂·8H₂O (Phase 3). The decomposition of Phase 5 is mainly responsible for reducing the mechanical strength of the MOCC pavement.

The Dahongliutan granitic pluton, in the eastern part of the West Kunlun orogenic belt, provides significant insights for studying the tectonic evolution of West Kunlun. This paper presents a systematic study of LA-ICP-MS zircon U-Pb age, major and trace elements, Sr-Nd-Hf isotopes, and the first detailed Li isotope analysis of the Dahongliutan pluton. LA-ICP-MS zircon U-Pb dating shows that the Dahongliutan granites were emplaced in the Late Triassic ((213±2.1) Ma). Geochemical data show relatively high SiO₂ contents (68.45 wt%–73.62 wt%) and aluminum saturation index (A/CNK=1.11–1.21) indicates peraluminous high-K calc-alkaline granite. The Dahongliutan granites are relatively high in light rare earth elements (LREE) and large ion lithophile elements (LILEs) (e.g., Rb, K, Th), and relatively depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, P, Ti). The ε_Nd(t) values range from −8.71 to −4.73, and (⁸⁷Sr/⁸⁶Sr)_i=0.7087–0.71574. Zircons from the pluton yield ¹⁷⁶Hf/¹⁷⁷Hf values of 0.2826181 to 0.2827683, and ε_Hf(t) values are around 0; the two-stage Hf model ages range from 0.974 to 1.307 Ga. The δ⁷Li values are 0.76‰–3.25‰, with an average of 2.53‰. Isotopic compositions of the pluton suggest a mixed trend between the partial melting of the Middle Proterozoic ancient crustal material and a juvenile mantle-derived material. This study infers that the Dahongliutan rock mass is formed in the post-collisional extension environment, when the collision between South Kunlun and the Tianshuihai terranes results in the closure of the Palaeo-Tethys. The mantle-derived magma results in partial melting of the lower crust.

Based on the element geochemistry and biomarkers of the oil shale from the Chang 7 sub-unit in the southern Ordos Basin, the depositional conditions and organic source of the oil shale are discussed. Biomarkers analyses show that the oil shale has a homologous organic matter source, with a mix of plankton and advanced plants. U/Th and V/Ni ratios suggest that the redox condition is dominated by a reducing condition, and the degree of anoxia in the Tongchuan area is higher than that of the Xunyi area. Sr/Ba ratios illustrate that the oil shale is deposited in fresh water and the paleosalinity in the Tongchuan area is slightly higher. Fe/Ti ratios imply that the Tongchuan area underwent obvious hydrothermal fluid activities. Sr/Cu ratios show warm and humid paleoclimate in both areas. As assessed by (La/Yb)_NASC, the deposition rate in the Tongchuan area is relatively lower. Fe/Co and Th/U ratios suggest that the paleo-water-depth in the Tongchuan area is deeper. The source rock could have the advance plants source, which must have close relationship with the Qinling orogeny. Comparing the paleoenvironment, the Tongchuan area has better depositional conditions, and is the key oil shale exploration area in the southern Ordos Basin.

The Lunggar iron deposit belongs to the Bangong-Nujiang metallogenic belt and is located in central Lhasa on the Tibetan Plateau. In the Lunggar deposit, iron mineralization formed in the skarnization contact zone between the Early Cretaceous granodiorite and the late Permian Xiala Formation limestone. In this study, we achieved detailed zircon U-Pb-Hf isotopes and mineral chemistry for the Early Cretaceous granodiorite. Zircon U-Pb dating results indicate that the Early Cretaceous granodiorite emplaced at ca. 119 Ma. Based on the trace elements in zircons and the mineral chemical composition of amphibole and biotite, the Early Cretaceous granodiorite was believed to form under condition of high temperature (>700 °C), low pressure (100–400 MPa), and relatively high oxygen fugacity (lg/O₂)(−13.6 to −13.9) and H₂O content (4%–8%). Zircon trace elements, Hf isotope and biotite chemistry collectively reveal that significant juvenile mantle-derived magmas contributed to the source of the granodiorite. The relatively high log/O₂ and shallow magma chamber are beneficial for skarn iron mineralization, implying remarkable potential for further prospecting in the Lunggar iron deposit.

The Pamir plateau may have been a westward continuation of Tibet plateau. Meanwhile, the Rushan-Pshart suture is correlative to the Bangong-Nujiang suture of Tibet, and the Central Pamir is the lateral equivalent of the Qiangtang Block. We present the first detailed LA-ICPMS zircon U-Pb chronology, major and trace element, and Lu-Hf isotope geochemistry of Taxkorgan two-mica monzogranite to illuminate the Tethys evolution in central Pamir. LA-ICPMS zircon U-Pb dating shows that two-mica monzogranite is emplaced in the Cretaceous (118 Ma). Its geochemical features are similar to S-type granite, with enrichment in LREEs and negative Ba, Sr, Zr and Ti anomalies. All the samples show negative zircon εHf(t) values ranging from −17.0 to −12.5 (mean −14.5), corresponding to crustal Hf model (T_DM2) ages of 1906 to 2169 Ma. It is inferred that these granitoids are derived from partial melting of peliticmetasedimentary rocks analogous to the Paleoproterozoic Bulunkuole Group, predominantly with muscovite schists component. Based on the petrological and geochemical data presented above, together with the regional geology, this work provides new insights that Bangong-Nujiang Ocean closed in Early Cretaceous(120–114 Ma).

The Zhuxi W(Cu) skarn deposit, the world’s largest tungsten deposit is newly discovered in Jingdezhen city, northeastern Jiangxi province, China. It mainly occurs near the contact zone between the Yanshanian granites and the Late Paleozoic carbonate rocks. Three types of mineralization including skarn type, altered granite type and quartz vein-veinlet type orebodies have been observed. In this study, the ⁴⁰Ar⁻³⁹Ar age of hydrothermal muscovite coexisting with copper mineralization in the altered granite type orebody formed near the unconformity interface is determined by step-heating technology using CO₂ laser. The plateau age, isochron age, and inverse isochron age of muscovite are (147.39±0.94) Ma, (147.2±1.5) Ma, and (147.1±1.5) Ma, respectively. These ages are almost identical to the ages of ore-related granite and other mineralization types in the Zhuxi W(Cu) deposit, indicating that the Cu mineralizations occurred at the shallow depth and near the unconformity interface are contemporaneous during the Late Jurassic. This further suggested that the acompanied W and Cu mineralization in the Zhuxi W(Cu) deposit which may be controlled by the magma source is enriched in both W and Cu.

Despite the presence of a large area of andesite in the Sayaburi Province of Laos, it has received very little attention. Based on a combination of detailed field investigations, geochronology and geochemical analysis, this study aims to explore the geochemical, Sr-Nd isotopic, and source rock characteristics, as well as the genesis and tectonic setting of the andesite in this region. In the Sayaburi Province, the andesite zircon U-Pb age is (241.2±1.2) Ma. The andesite rock is classified in the metaluminous-weak peraluminous calc-alkaline series. The light rare-earth elements (LREEs) are enriched and characterized by clear fractionation, whereas heavy rare-earth elements (HREEs) are relatively depleted and have no signs of fractionation. The average δEu is 0.96 with weak-or-no Eu anomalies. It is enriched in large ion lithophile elements such as Rb and K, while depleted in high field-strength elements such as Nb, Ta, P and Ti. For andesites in the Sayaburi Province, the (⁸⁷Rb/⁸⁶Sr)_t value ranges in 0.702849–0.704687, the εNd(t) value is between 3.53 and 4.77, the t_DM(t) value ranges in 633–835 Ma, and the t_DM2(t) ranges in 625–724 Ma. The results based on the synthesis of petrology, geochemistry, and regional tectonic background studies show that 1) the andesitic magma source in the study area is an enriched mantle, which is modified by subduction zone fluids; 2) the geotectonic background environment of the andesite in Sayaburi area is the continental island arc environment and related to the tectonic evolution of Jinghong-Nan-Uttaradit back-arc basin, which reflects that the magmatic source is enriched with a mantle wedge component modified by a subduction zone fluid (or melt).

The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a high-grade w(MnO)=8.92% to 18.76%) manganese deposit with low-phosphorus w(P₂O5)=0.08% to 0.16%) content. It also has a low total REEs contents (with an average of 101.3×10⁻⁶), and has inconspicuous Ce (0.81 to 1.29) and Eu (1.00 to 1.25) anomalies. lg(Ce/Ce^*) values are from −0.02 to 0.11. The ores have high SiO₂/Al₂O₃ and Al/(Al + Fe + Mn) ratios. In figures of Fe−Mn−[(Ni+Cu+Co)×10] and lgU−lgTh, all samples show that hydrothermal exhalative fluids played an important role during mineralisation. The δ¹³C_PDB and δ¹⁸O_SMOW values of eight ore samples are from −20.7‰ to −8.2‰ (with an average of −12.4%) and from 14.3‰ to 18.7‰ (with an average of 17.0‰), respectively. These carbon and oxygen isotopic features indicate that hydrothermal fluids derived from deep earth are participation in the metallogenic process, which is also supported by high paleo-seawater temperatures varying from 47.08 to 73.98 °C. Therefore, the geological and geochemical evidences show that the Qujiashan deposit formed from submarine exhalative hydrothermal sedimentation.

The ilvaite-bearing skarn associations in the Galinge skarn deposit were studied to determine their physicochemical formation conditions. A thermodynamic model setting pressure of 50 MPa (P_f=P_s=50 MPa) was set up to trace the skarn evolution. Petrographic evidence for replacement of garnet and magnetite by ilvaite in the early retrograde stage (Stage I) combined with thermodynamic modeling suggests that the alteration may have occurred at 400–470 °C under moderately high fO₂ with ΔlgfO₂(HM) ranges from −4 to −4.2. The model is based on a maximum pressure of 50 MPa calculated from magmatic amphibole geobarometer. The continuous breakdown of ilvaite with quartz to form ferro-actinolite and magnetite occur in the late retrograde stage (Stage II). The reactions occurred at 400-440°C under moderate fO₂ (ΔlgfO₂(HM): −4 to −4.4). In Stage III, the breakdown of ilvaite to form calcite, pyrite and ferroactinolite depends on XCO₂ which can be estimated to be in a range of 0.005 to 0.05, and the reaction would occur at higher temperatures with increasing XCO₂. Under these conditions, the breakdown occurs at 270–350 °C and low fO₂ (ΔlgfO₂(HM): up to −5.2). The thermodynamic model for continuous evolution from Stage I to Stage III completely records the conditions of the retrograde alteration, which is inconsistent with the thermobarometry imprints of fluid inclusions. Therefore, the petrography and phase relations of ilvaite are useful indicators of reaction conditions in various skarn deposit types.