Selective separation of silica from a siliceous-calcareous phosphate ore that had been sieved into different size fractions is investigated by a combination of chemical analysis,zeta potential measurement and FTIR and...Selective separation of silica from a siliceous-calcareous phosphate ore that had been sieved into different size fractions is investigated by a combination of chemical analysis,zeta potential measurement and FTIR and XPS techniques.Scrubbing is a better choice than flotation for removing silica from the coarse fractions.The P_2O_5 grade of the coarse fractions is increased to about 30%by scrubbing and the product yields are higher than those obtained by flotation.The silica in the fine fraction is separated by reverse flotation.An alkyl amine salt(DAH)is an effective collector and the P_2O_5 grade of the fine fraction can be increased by 7%to beyond 30%under acidic conditions.The higher zeta potential obtained using DAH suggests that it is more strongly absorbed onto the ore particles than the other cationic collectors. FTIR and XPS results confirm physical absorption of the cationic collector onto the ore surface.They also indicate that calcite is dissolved at low pH values,which increases the Si concentration on the ore surface.展开更多
Objective：We investigated whether disturbance of calcium and phosphate metabolism is associated with the presence and severity of calcific aortic valve disease （CAVD） in patients with normal or mildly impaired rena...Objective：We investigated whether disturbance of calcium and phosphate metabolism is associated with the presence and severity of calcific aortic valve disease （CAVD） in patients with normal or mildly impaired renal function. Methods：We measured serum levels of calcium, phosphate, alkaline phosphatase （AKP）, intact parathyroid hormone （iPTH）, 25-hydroxyvitamin D （25-OHD）, and biomarkers of bone turnover in 260 consecutive patients with normal or mildly impaired renal function and aortic valve sclerosis （AVSc） （n=164） or stenosis （AVS） （n=96） and in 164 age- and gender-matched controls. Logistic regression models were used to determine the association of mineral metabolism parameters with the presence and severity of CAVD. Results：Stepwise increases were observed in serum levels of calcium, phosphate, AKP, and iPTH from the control group to patients with AVS, and with reverse changes for 25-OHD levels （al P〈0.001）. Similarly, osteocalcin, procol agen I N-terminal peptide, andβ-isomerized type I col agen C-telopeptide breakdown products were significantly increased stepwise from the control group to patients with AVS （al P〈0.001）. In patients with AVS, serum levels of iPTH were positively, in contrast 25-OHD levels were negatively, related to trans-aortic peak flow velocity and mean pressure gradient. After adjusting for relevant confounding varia-bles, increased serum levels of calcium, phosphate, AKP, and iPTH and reduced serum levels of 25-OHD were in-dependently associated with the presence and severity of CAVD. Conclusions： This study suggests an association between mineral metabolism disturbance and the presence and severity of CAVD in patients with normal or mildly impaired renal function. Abnormal bone turnover may be a potential mechanism.展开更多
基金the National Key Technology R&D Program of China forthe support of this work(No.2007BAE58B01).
文摘Selective separation of silica from a siliceous-calcareous phosphate ore that had been sieved into different size fractions is investigated by a combination of chemical analysis,zeta potential measurement and FTIR and XPS techniques.Scrubbing is a better choice than flotation for removing silica from the coarse fractions.The P_2O_5 grade of the coarse fractions is increased to about 30%by scrubbing and the product yields are higher than those obtained by flotation.The silica in the fine fraction is separated by reverse flotation.An alkyl amine salt(DAH)is an effective collector and the P_2O_5 grade of the fine fraction can be increased by 7%to beyond 30%under acidic conditions.The higher zeta potential obtained using DAH suggests that it is more strongly absorbed onto the ore particles than the other cationic collectors. FTIR and XPS results confirm physical absorption of the cationic collector onto the ore surface.They also indicate that calcite is dissolved at low pH values,which increases the Si concentration on the ore surface.
基金Project supported by the Science and Technology Commission of Shanghai Municipality(No.114119a8800),China
文摘Objective：We investigated whether disturbance of calcium and phosphate metabolism is associated with the presence and severity of calcific aortic valve disease （CAVD） in patients with normal or mildly impaired renal function. Methods：We measured serum levels of calcium, phosphate, alkaline phosphatase （AKP）, intact parathyroid hormone （iPTH）, 25-hydroxyvitamin D （25-OHD）, and biomarkers of bone turnover in 260 consecutive patients with normal or mildly impaired renal function and aortic valve sclerosis （AVSc） （n=164） or stenosis （AVS） （n=96） and in 164 age- and gender-matched controls. Logistic regression models were used to determine the association of mineral metabolism parameters with the presence and severity of CAVD. Results：Stepwise increases were observed in serum levels of calcium, phosphate, AKP, and iPTH from the control group to patients with AVS, and with reverse changes for 25-OHD levels （al P〈0.001）. Similarly, osteocalcin, procol agen I N-terminal peptide, andβ-isomerized type I col agen C-telopeptide breakdown products were significantly increased stepwise from the control group to patients with AVS （al P〈0.001）. In patients with AVS, serum levels of iPTH were positively, in contrast 25-OHD levels were negatively, related to trans-aortic peak flow velocity and mean pressure gradient. After adjusting for relevant confounding varia-bles, increased serum levels of calcium, phosphate, AKP, and iPTH and reduced serum levels of 25-OHD were in-dependently associated with the presence and severity of CAVD. Conclusions： This study suggests an association between mineral metabolism disturbance and the presence and severity of CAVD in patients with normal or mildly impaired renal function. Abnormal bone turnover may be a potential mechanism.
