This study aims to remove the metals(inorganic and heavy metals) in waste foundry sand(WFS)via chemical washing method. Washed waste foundry sand(WWFS) samples were obtained by using triptych washing successively with...This study aims to remove the metals(inorganic and heavy metals) in waste foundry sand(WFS)via chemical washing method. Washed waste foundry sand(WWFS) samples were obtained by using triptych washing successively with 5 M HCl, 5 M H_2SO_4 and 5 M NaOH solutions. Analysis on functional groups,micropores, heavy metals,and inorganic components of WFS and WWFS was carried out by using FT-IR, SEM and XRF. Results show that the concentration values of some inorganic components such as Ca, Fe, Mg, S were decreased, and the maximum removal percentage of these inorganic components are 47%, 19%, 32%, and 8%,respectively. The concentration values for each of the heavy metals of WWFS are below of limit values given in App-3 List of Regulation on General Principles of Waste Management. The removal percentages of Pb, As and Zn elements are 100%, 71%, and 40%, respectively. The findings of this research suggest that WWFS can be used in more applications due to its ability to remove heavy metals and some other inorganic components.展开更多
According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the pr...According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.展开更多
Silica is becoming more attractive as plant nutrient for non-graminae crops particularly in relation with drought-stress tolerant. Many efforts have been conducted to obtain an efficient technique to produce silica fe...Silica is becoming more attractive as plant nutrient for non-graminae crops particularly in relation with drought-stress tolerant. Many efforts have been conducted to obtain an efficient technique to produce silica fertilizer worldwide, but the results are varying considerably due to various factors including raw material and extraction technique. This study was carried out to develop an efficient extraction technique for ortho-silicic acid (OSA-H4SiO4) from a Bangka-Belitung quartz sand by employing acid-base dissolution method. A 325-mesh size quartz sand was boiled in HCl solution at various concentrations. The optimum concentration was then used in the following experiment at several different volumes of solution. The sand obtained from optimum concentration and volume of HCl solution was then reacted with different amounts of NaOH (s), and heated until a wet mixture was obtained. As a reference the best extraction conditions were applied to a natural zeolite sample. All OSA analyses were done in triplicates with spectrophotometric method. Supporting evidences were collected from x-ray diffraction and scanning-electron-microscopy analyses of the treated samples. The yield of quartz sand-originated OSA was 183 g·kg-1 and significantly increased linearly with increasing weight of NaOH (R2 = 0.99**), whereas that from zeolite was only 104.2 g·kg-1 at 80 g NaOH. XRD and SEM data confirmed the evidences that the acid-base extraction disrupted the quartz mineral structure and as a consequence releasing more water soluble OSA.展开更多
文摘This study aims to remove the metals(inorganic and heavy metals) in waste foundry sand(WFS)via chemical washing method. Washed waste foundry sand(WWFS) samples were obtained by using triptych washing successively with 5 M HCl, 5 M H_2SO_4 and 5 M NaOH solutions. Analysis on functional groups,micropores, heavy metals,and inorganic components of WFS and WWFS was carried out by using FT-IR, SEM and XRF. Results show that the concentration values of some inorganic components such as Ca, Fe, Mg, S were decreased, and the maximum removal percentage of these inorganic components are 47%, 19%, 32%, and 8%,respectively. The concentration values for each of the heavy metals of WWFS are below of limit values given in App-3 List of Regulation on General Principles of Waste Management. The removal percentages of Pb, As and Zn elements are 100%, 71%, and 40%, respectively. The findings of this research suggest that WWFS can be used in more applications due to its ability to remove heavy metals and some other inorganic components.
文摘According to the characteristics of stone along the KKH-2 project in Pakistan, the applicability of gravel and machine-made sand for road engineering was studied. Through investigation, the types of stone along the project were relatively simple, and the stone materials used for road construction were mainly limestone, sandstone and pebbles, and the reserves?were?abundant. The experiment research and analyses comparisons of the parameters and road performance characteristics of natural gravel materials were carried out, and the design parameters and road performance indicators of natural grit in the current code were supplemented and adjusted to make it more suitable for Pakistan to use natural gravel materials for road construction. Thesis combines the project,?proposing that mechanism sand and natural sand mixed concrete?is?not inferior?tonatural sand mixed concrete in terms of technical performance, and the overall cost is lower than that of natural sand mixed concrete. The research results are of great significance for saving engineering construction costs, ensuring road performance and prolonging service life.
文摘Silica is becoming more attractive as plant nutrient for non-graminae crops particularly in relation with drought-stress tolerant. Many efforts have been conducted to obtain an efficient technique to produce silica fertilizer worldwide, but the results are varying considerably due to various factors including raw material and extraction technique. This study was carried out to develop an efficient extraction technique for ortho-silicic acid (OSA-H4SiO4) from a Bangka-Belitung quartz sand by employing acid-base dissolution method. A 325-mesh size quartz sand was boiled in HCl solution at various concentrations. The optimum concentration was then used in the following experiment at several different volumes of solution. The sand obtained from optimum concentration and volume of HCl solution was then reacted with different amounts of NaOH (s), and heated until a wet mixture was obtained. As a reference the best extraction conditions were applied to a natural zeolite sample. All OSA analyses were done in triplicates with spectrophotometric method. Supporting evidences were collected from x-ray diffraction and scanning-electron-microscopy analyses of the treated samples. The yield of quartz sand-originated OSA was 183 g·kg-1 and significantly increased linearly with increasing weight of NaOH (R2 = 0.99**), whereas that from zeolite was only 104.2 g·kg-1 at 80 g NaOH. XRD and SEM data confirmed the evidences that the acid-base extraction disrupted the quartz mineral structure and as a consequence releasing more water soluble OSA.
