Sulfuric Acid Baking—Water Leaching for Gold Enrichment and Arsenic Removal from Gold Concentrate

During the roasting of gold concentrate to improve gold recovery, arsenic is released into the air and valuable elements such as Fe, Cu, Zn, and Pb are converted into oxide minerals. In this research, we evaluated the release of As and the loss of valuable metals during the acid baking and hot water leaching processes used for gold concentrate. The acid bake tests were conducted for gold concentrate using an electric furnace by applying various concentrations of H2SO4 solution under different baking times. The water leaching process was enacted using 70 °C water for the baked samples. Chemical and mineral compositions of the raw and treated samples were analyzed using AAS and XRD, respectively. The results show that soluble metal sulfates, such as rhomboclase and mikasite, were formed in the baked samples, and that the leaching of valuable metals (Fe, Cu, Zn, and Pb) was accelerated during the hot water leaching procedure. During acid baking, arsenic was partially removed by volatilization, and the rest of the arsenic-containing minerals were converted to soluble minerals. The soluble arsenic-containing mineral resulted in a dissolution that was 60 times higher than in the roasted sample. The maximum gold grade of solid residues increased up to 33% through the acid baking–water leaching process. It was confirmed that acid baking with H2SO4 prevented As release into the air, as well as the recovery of valuable metals through hot water leaching, such as Fe, Cu, Zn, and Pb, which were formerly discarded in the tailings.

Diagnosis and Optimization of Gold Ore Flotation Circuit via Linear Circuit Analysis and Mass Balance Simulation

The aim of this study is to diagnose and optimize a closed multistage gold ore flotation circuit in an operational industrial plant. Linear circuit analysis (LCA), a partition-based model, and a mass balance model using flotation first-order kinetics are employed to diagnose the current process. The result shows that the current circuit operates with high recovery but the gold grade of the final concentrate is low owing to the low buoyancy ratio. Hence, several alternative circuits with different streamlines and cell arrangements are proposed and simulated using LCA and a mass balance model. The result suggests that if the current process is changed to an alternative circuit in which the floated product stream of the rougher bank is changed, then the gold grade of the concentrate can be improved by 128%. Finally, the current circuit is optimized by changing it to an alternative circuit. This study provides a methodology for adapting the simulation of optimization for the flotation circuit of an industrial plant via LCA and mass balance simulation.

Handgrip Strength During Admission for COPD Exacerbation: Impact on Further Exacerbation Risk

Background: Low handgrip strength (HGS) is independently associated with a higher exacerbation risk in smokers with stable chronic obstructive pulmonary disease (COPD); however, the relationship between HGS on admission for COPD exacerbation admission and further exacerbation risk remains unclear. This study aimed to investigate the relationship between HGS and further exacerbation risk in patients admitted for COPD exacerbation. Methods: We enrolled patients admitted for COPD exacerbation between January 2018 and June 2019 who underwent HGS measurement within 3 days after admission. The primary endpoint was exacerbations within 12 months after the index admission. We analyzed the relationships among demographics, HGS, pulmonary function parameters, and acute exacerbation events. Results: Among 43 enrolled patients, 31 (72.1%) presented HGS weakness (22.1 ± 4.1 kg). Forced expiratory volume in one second (FEV1) and FEV1 percentage of predicted value (FEV1 predicted%) were significantly lower in patients with HGS weakness (0.82 ± 0.20 vs. 1.59 ± 0.77, p = 0.018; 36.2 ± 10.4% vs. 66.3 ± 22.2, p = 0.004, respectively). Moreover, patients with HGS weakness were more likely to have severe GOLD grade IV (19.4% vs. 8.3%, p = 0.002). Finally, patients with HGS weakness showed a significantly higher rate of emergency room visits within 6, 9, and 12 months after the index admission (0.81 ± 1.30 vs. 0.08 ± 0.29, p = 0.045; 1.26 ± 1.59 vs. 0.17 ± 0.38, p = 0.019; 1.48 ± 1.86 vs. 0.25 ± 0.62, p = 0.027, respectively). Conclusions: HGS weakness measured upon admission for COPD exacerbation was associated with a higher risk of further exacerbation. Trial registration: ClinicalTrials.gov Identifier: NCT04885933

New perspective Reza gold deposit (Gedabek ore district, Lesser Caucasus, Azerbaijan)

The article describes Reza gold deposit of Ugur exploration area located in Geda- bek Ore District of the Lesser Caucasus in NW of Azerbaijan. It is established that main mineralization in the Reza gold deposit consists of hematite-barite-quartz-kaoline veins- veinlets and breccia, pyrite stock-stockverk and quartz-sulfide veins. On the main orebody surface center secondary quartzites with vein-veinlets barite-hematite mineralization have occured over which remain accumulations of hydrous ferric oxides cementing breccias of quartz and secondary quartzites. “Reddish mass” is also observed in erosion parts, being an oxidation product of stock and stockverk limonite-hematite ores. Representing typical gossans, these accumulations by the data of trenches for thickness about 5-10 m contain gold 0.3-3.5 ppm and silver 1.0-45.0 ppm. There are three zones of gold mineralization within the Reza gold deposit: oxide mineralization; transition zone mineralization; sulfide mineralization. The oxide gold mineraliza- tion consists of clay-gravel weathering crust of kaolinite type. The gold-bearing mineralization has been oxidized to a depth of ap- proximately 50-100 meters. Typically, the gold mineralization is coarser and a minor increase in gold grade occurs within the oxides compared to the original rocks. The nugget effect increase in the gold grade of the oxides does not exceed approximately 10%. Deposit alteration signature has characteristics which suggest the current outcrop level may be near the top of a mineralized, gold-bearing high sulfidation epithermal (HSE) system. The gold mineralization at the deposit is interpreted as forming in shallow high sulfidation epith- ermal systems. The mineralization has been noted in well-confined hydrothermal breccia and associated with pyrite stock-stockwork. The majority of the deposit material and current estimates are formed within the barite-hematite-quartz-kaoline mineralization in the secondary quartzite rocks. The main brecciation and stockwork are hosted within secondary quartzite, sometime massive silicified andesite porphyritic rocks.

Lithogeochemical exploration for delineating primary gold occurrences in West Kao area, North Halmahera District, North Maluku Province

Halmahera Island retains several gold deposits. One of the gold deposits is called as low sulphidation epithermal (LSE) quartz veins which is currently being mined and is situated in the Gosowong goldfield. The veins mostly originated in N-S and NNE-SSW direction. This study is aimed to determine the prospect area in the northern portion of Gosowong goldfield covering the West Kao sub district based on surface mapping and rock/float- and BLEG stream sediment survey. A total of 16 rock/vein float and 120 BLEG samples were analyzed by FA/AAS and CNO2 cyanide leach methods, respectively. The study area is occupied by tuffaceous sandstone, andesite, porphyritic andesite and lava andesite units. In the eastern part, tuffaceous sandstone is suffered from argillic and propylitic alteration, which may be controlled by the NW-SE-trending structures. The gold grade of rock/float samples is up to 0.044 ppm. BLEG data indicates a calculated threshold of 10 ppb for Au and 72 ppb for Ag. The highest Au and Ag contents (anomalies) are identified in the eastern part of the study area. This is spatially (and maybe genetically) related to the argillic-altered tuffaceous sandstone, structures and occurrences of quartz vein floats. To follow up this finding, a detailed exploration is recommended to be conducted within the prospect area.

Deterioration and Mortality Risk of COPD Patients Not Fitting into Standard GOLD Categories: Results of the COSYCONET Cohort

<b><i>Background:</i></b> Patients with COPD-specific symptoms and history but FEV₁/FVC ratio ≥0.7 are a heterogeneous group (former GOLD grade 0) with uncertainties regarding natural history. <b><i>Objective:</i></b> We investigated which lung function measures and cutoff values are predictive for deterioration according to GOLD grades and all-cause mortality. <b><i>Methods:</i></b> We used visit 1–4 data of the COSYCONET cohort. Logistic and Cox regression analyses were used to identify relevant parameters. GOLD 0 patients were categorized according to whether they maintained grade 0 over the following 2 visits or deteriorated persistently into grades 1 or 2. Their clinical characteristics were compared with those of GOLD 1 and 2 patients. <b><i>Results:</i></b> Among 2,741 patients, 374 GOLD 0, 206 grade 1, and 962 grade 2 patients were identified. GOLD 0 patients were characterized by high symptom burden, comparable to grade 2, and a restrictive lung function pattern; those with FEV₁/FVC above 0.75 were unlikely to deteriorate over time into grades 1 and 2, in contrast to those with values between 0.70 and 0.75. Regarding mortality risk in GOLD 0, FEV₁%predicted and age were the relevant determinants, whereby a cutoff value of 65% was superior to that of 80% as proposed previously. <b><i>Conclusions:</i></b> Regarding patients of the former GOLD grade 0, we identified simple criteria for FEV₁/FVC and FEV₁% predicted that were relevant for the outcome in terms of deterioration over time and mortality. These criteria might help to identify patients with the typical risk profile of COPD among those not fulfilling spirometric COPD criteria.

Association between serum CCL-18 and IL-23 concentrations and disease progression of chronic obstructive pulmonary disease

This study aimed to investigate the association between serum concentrations of chemokine (C–C Motif) ligand 18 (CCL-18) and interleukin 23 (IL-23) and clinical parameters of chronic obstructive pulmonary disease (COPD). The serum concentrations of CCL-18 and IL-23 were tested by enzyme linked immunosorbent assay (ELISA). The association between their concentrations and clinical parameters of COPD patients were analyzed by linear regression, logistic regression and ROC curve. The results showed that the serum concentrations of CCL-18 and IL-23 in COPD patients were increased compared with healthy people (P < 0.001) and that patients with acute exacerbation of COPD (AECOPD) had higher serum CCL-18 and IL-23 concentrations than stable patients (P < 0.001). Synergistic increase of CCL-18 and IL-23 in COPD patients was positively correlated with COPD patients' higher GOLD grade (P < 0.001), higher mMRC score (P < 0.001) and longer medical history (P < 0.001), but negatively correlated with the forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (P < 0.001) and FEV1% predicted (P < 0.001). The serum concentrations of CCL-18 and IL-23 were most related to the GOLD grade (OR = 2.764 for CCL-18 and OR = 4.215 for IL-23) and detection of both showed considerable sensitivity (72.57% for CCL-18 and 76.92% for IL-23) and specificity (92.50% for CCL-18 and 77.5% for IL-23) in identifying COPD. Increased serum concentrations of CCL-18 and IL-23 correlated with the disease progression of COPD and they could be used as biomarkers for disease evaluation of COPD.

Mitochondrial dysfunction in airways and quadriceps muscle of patients with chronic obstructive pulmonary disease

Background Mitochondrial damage and dysfunction have been reported in airway and quadriceps muscle cells of patients with chronic obstructive pulmonary disease (COPD). We determined the concomitance of mitochondrial dysfunction in these cells in COPD. Methods Bronchial biopsies were obtained from never- and ex-smoker volunteers and COPD patients (GOLD Grade 2) and quadriceps muscle biopsies from the same volunteers in addition to COPD patients at GOLD Grade 3/4 for measurement of mitochondrial function. Results Decreased mitochondrial membrane potential (ΔΨm), increased mitochondrial reactive oxygen species (mtROS) and decreased superoxide dismutase 2 (SOD2) levels were observed in mitochondria isolated from bronchial biopsies from Grade 2 patients compared to healthy never- and ex-smokers. There was a significant correlation between ΔΨm and FEV1 (% predicted), transfer factor of the lung for carbon monoxide (TLCOC % predicted), 6-min walk test and maximum oxygen consumption. In addition, ΔΨm was also associated with decreased expression levels of electron transport chain (ETC) complex proteins I and II. In quadriceps muscle of Grade 2 COPD patients, a significant increase in total ROS and mtROS was observed without changes in ΔΨm, SOD2 or ETC complex protein expression. However, quadriceps muscle of GOLD Grade 3/4 COPD patients showed an increased mtROS and decreased SOD2 and ETC complex proteins I, II, III and V expression. Conclusions Mitochondrial dysfunction in the airways, but not in quadriceps muscle, is associated with airflow obstruction and exercise capacity in Grade 2 COPD. Oxidative stress-induced mitochondrial dysfunction in the quadriceps may result from similar disease processes occurring in the lungs.

The diagnostic value of homocysteine for the occurrence and acute progression of chronic obstructive pulmonary disease

Background This study aimed to evaluate whether the Homocysteine (Hcy) level was elevated in chronic obstructive pulmonary disease (COPD) patients and its correlation with the occurrence and acute progression of COPD. Methods From November 2014 to November 2015, COPD patients were enrolled from Beijing Chao-yang Hospital, and the the biological and clinical data were collected. These patients were tested in the non-acute exacerbation period and the acute exacerbation period, so they were defined as AECOPD group and Non-AECOPD group. Besides, 50 healthy subjects were recruited and defined as control group. Total plasma Hcy levels (antibodies-online, USA) were determined by enzyme-linked immunosorbent assay. Correlation analysis was used to analyze the correlation between serum Hcy level and ventilatory function. Using ROC curve, the diagnostic value of Hcy for the occurrence and acute progression of COPD was explored. Results In this study, we found that Hcy levels in the Non-AECOPD group or the AECOPD group were significantly higher than those in the control group (P < 0.001). Meanwhile, compared with the Non-AECOPD group, the Hcy level in the AECOPD group was significantly higher (P < 0.001). In addition, according to the classification of GOLD grade, there was significant difference in the Hcy level among different GOLD grade groups (P < 0.001). The correlation analysis showed that in the AECOPD group and the Non-AECOPD group, Hcy levels presented a negative correlation with FEV1(r < 0). Meanwhile, FEV1% was also negatively correlated with Hcy level (r < 0). ROC curve analysis showed that when the cutoff value was set to 10.8 μg/ml, the specificity, sensitivity and AUC were the best, which were 0.980, 0.800, and 0.945, respectively. Besides, our results showed that when the cutoff value was set to 14.0 μg / ml, the specificity, sensitivity and AUC were the best, which were 0.846, 0.680, and 0.802, respectively. In addition, compared with the prediction of acute progression of COPD, when Hcy level predicted the occurrence of COPD, its specificity (0.980 vs. 0.846, P < 0.001) and sensitivity (0.800 vs. 0.680, P < 0.001) were significantly higher. Conclusion Hcy level is positively correlated with the severity of COPD patients, which has predictive value for the occurrence of COPD and acute progression.