Liming By-products Research Articles

Biological Aspects of Metal Waste Reclamation with Biosolids

Smelter waste deposits pose an environmental threat worldwide. Biosolids are potentialy useful in reclamation of such sites. Biological aspects of revegetation of Zn and Pb smelter wastelands using biosolids are discussed in this report. The goal of the studies was to assess to what extent biosolid treatment would support ecosystem functioning as measured by biological indicators such as enzyme activities of revegetated metal waste or plant growth. Another crucial aspect was related to the assessment of metal transfer to the ecosystem which could affect the health of local fauna and also create a food chain risk. A field experiment was conducted on a smelter waste deposit in Piekary Slaskie, Silesia, Poland, with two separate fields - established on wastes from the Welz and Doerschel smelting processes. The tested methods allowed revegetation of the fields - application of municipal biosolid at the rate 300 dry t ha(-1) combined with the incorporation of commercial lime in a mixed oxide and carbonate form at the rate of 1.5 and 30 t for Welz waste or use of a 30 cm by-product lime cap followed by incorporation of biosolid at a rate of 300 t ha(-1) for the more acidic Doerschel waste. Studies on biological activities demonstrated that the reclamation methods used are an effective way to establish new, fully-functioning ecosystems that support plant growth. They also provided strong evidence that forage crops grown on Zn, Cd and Pb contaminated sites reclaimed using lime and biosolids do not pose identified risk for wildlife and food safety.

SOIL SOLUTION DYNAMICS INTO PALEXERULT AMENDED WITH GYPSUM AND LIME BY-PRODUCTS

A laboratory experiment involving the use of leaching columns reproducing the topmost part of a clayey-skeletal kaolinitic acid thermic plinthic Palexerult amended with lime and gypsum by-products was used to study changes in soil solution composition during two leaching cycles. The lime amendment mainly affected the composition of the soil solution of the Ap horizon, where it increased pH and Ca and decreased the F and Al concentrations. Gypsum by-products caused an initial pH decrease in the soil solution; however, as the gypsum was leached, the pH rose and eventually exceeded that of both Ap and AB in the controls. After the gypsum by-product application, Mg and Na strongly increased, but afterward decreased to levels lower than those in the controls; Al contents increased in the first water extracts from Ap and AB horizons and that of F in all extracts from Ap and most from AB. The variation of the Ca and SO42− concentrations in the AB horizon was influenced by surface sorption and precipitation.

Experimental study on moisture evaporation of lime wastes and marine clay: implications for landfill storage management

A large quantity of by-product lime wastes with high water content produced from chemicals manufacturing processes has been stacked in an open area in Incheon, Korea. Highly alkaline leachate and fine dust emanating from the stacked lime wastes caused an environmental concern in the city. So evaporative drying and stabilization of the fine-grained wastes and use of the on site marine clay as a natural geomembrane liner using drying hardening were considered as a part of a landfill construction plan. Treatment of the lime wastes and marine clay was focused on maximizing the evaporative drying and the density. Evaporation experiments were conducted in field condition to understand evaporation characteristics and to evaluate actual evaporation rate of the lime wastes and marine clay. Local Class A pan evaporation data from a nearby weather station for last 30 years indicated that mean annual and monthly evaporations were 1,178.5 and 98.2 mm, respectively. Relative evaporations of the sludge lime, cake lime, and marine clay compared with the pan evaporation were 114.9, 61.9, and 119.0%, respectively. Estimates of annual evaporations from storage surfaces in the field based on the relative evaporation data were 1,353.6, 729.1, and 1,402.2 mm for the sludge lime, cake lime, and the marine clay, respectively. And annual net evaporations considering rainfall effect were estimated as between 879.9 and 1,082.9 mm for the lime sludge, between 473.9 and 583.3 mm for the lime cake, and between 981.5 and 1,191.9 mm for the marine clay. It was expected that the actual field evaporation rate would be varied with the moisture contents of the lime and the clay. Results of these experiments will provide useful implications for the drying behavior of the by-product lime and the marine clay and landfill or management plan of the storages.

AGRONOMIC IMPLICATIONS OF THE SUPPLY OF LIME AND GYPSUM BY-PRODUCTS TO PALEXERULTS FROM WESTERN SPAIN

A laboratory experiment with leaching columns reproducing the topmost portion (Ap and AB horizons) of a Palexerult from western Spain was conducted to compare the efficiency of limestone (L), gypsum (G), and various lime and gypsum by-products (sugar foam waste, phosphogypsum [PG], and red gypsum [RG]) to alleviate Al toxicity and improve soil productivity. The effect of the previous five amendments on composition changes in the exchange complex and the soil saturation extract was examined after one or two leaching cycles (equivalent to as many years of field precipitation). The productivity of the Ap horizon after the first leaching cycle was assessed by growing wheat (Triticum aestivum var. Jabato) in a greenhouse. The lime by-products increased the pH of the Ap horizon and the Ca content of the exchange complex to a greater extent than the gypsum amendments; in addition, the former minimized the Al content of the exchange complex and the saturation extract. Changes in the AB horizon were much less marked, and the sugar foam waste was a better liming material than limestone. The changes in the exchange complex and saturation extract from gypsum amendments followed a more complex pattern and affected both horizons (Ap and AB). The pH of the soil was initially decreased relative to the controls through a "salt effect" and then increased after the second leaching cycle, when most of the gypsum was leached from the soil. In both horizons, the Ca content was increased, and the Al content of the exchange complex decreased-albeit to a lesser extent than with the lime amendments in Ap; by contrast, exchangeable Mg and Na were lost in substantial amounts in the first leaching cycle; K losses were comparatively smaller. After the first leaching cycle, aluminum-fluoride ion pairs were the most active Al species in the extracts from Ap and AB in PG amended columns; on the other hand, the aluminum sulfate ion pairs were the most active in the extracts from the G- and RG-amended columns. After the second leaching cycle, the activity of Al3+-the most phytotoxic ionic species of Al-in the Ap extracts from all calcium carbonate-amended columns decreased, whereas that in the gypsum-amended soil only decreased in the PG-treated columns; in the AB horizon, however, the extracts from all gypsic amendments decreased the Al3+ activity, with respect to control and lime amendments. The calcium aluminum balance (Noble et al., 1988) was increased by all treatments. All lime and gypsum amendments-particularly sugar foam waste-increased productivity relative to the controls. Of the three gypsum amendments, RG had the greatest impact on productivity; this can be ascribed to its Zn content, which was very low in the natural soil.

부산석회를 이용한 납석광산 폐석의 중화처리

Numerous abandoned or closed mines are present in the steep mountain valleys in Korea due to the depression of the mining industry since the late 1980s. From the mines, enormous amounts of wastes were dumped on the slopes causing sedimentation and acid mine drainage to be discharged directly into streams causing detrimental effects on surrounding environment. Objective of this research was to evaluate the feasibility of the lime cake by-product from the soda ash production (Solvay process) to neutralize the pyrophyllite mine wastes, which have discharged the acid drainage to soil and stream in the watershed. The pH of mine wastes was strongly acidic at pH 3.67 containing over 16% of and 11% of . Whereas the lime cake by-product was strongly basic at pH 9.97 due to high contents of CaO, MgO and as major components. Column experiments were conducted to test the neutralizing capacity of the lime cake by-product for the acidic pyrophyllite mine wastes. The column packed with the wastes (control) was treated with the lime cake by-product, calcium carbonate, the dressing soil or combination. The distilled water was eluted statically through the column and the leachate was collected for the chemical analyses. Treatments of the mine wastes with the lime cake by-product (or calcium carbonate) as mixtures increased pH of the leachate from . Concentrations of Fe and Al in the leachate were also decreased below 1.0 mg . A Similar result was observed at the combined treatments of the mine waste, the lime by-product (or calcium carbonate) and the dressing soil. The results indicated that the lime cake by-product could sufficiently neutralize the acid drainage from the pyrophyllite mine wastes without dressing soils.

Characterization and use of pulp mill fly ash and lime by-products as road construction amendments

Fly ash and lime by-products are the two main waste streams generated by the pulp and paper industry. Traditionally, these wastes are disposed of either in surface impoundment or landfills. Greater environmental concerns and limited land availability have made these disposal practices increasingly unacceptable and costly. Thus, the objective of this study was to determine the feasibility of beneficial utilization alternatives with emphasis on their use as road construction amendment materials based on technical, economical, and environmental considerations. The experiments were conducted to comprehensively characterize the chemical, physical, engineering, and environmental properties for both waste samples and their mixtures prepared with local soils at different curing conditions. Field road tests were then conducted to verify and assess the performance of the mixtures in terms of load bearing capacity, serviceability, and compaction. The results showed that pulp mill wastes would have little adverse environmental impact and could be used as road construction amendments to improve soil strength and reduce deformation. This improvement was significantly affected by soil types, moisture contents, and waste addition rates. During waste-soil amendment, the metal leachability would be further reduced by the occurrence of solidification processes.Key words: wood ash, fly ash, lime by-products, solid waste management, pulp mill waste, waste utilization, leaching tests.

Characterization and use of pulp mill fly ash and lime by-products as road construction amendments

Characterization and use of pulp mill fly ash and lime by-products as road construction amendments

Radiation dose estimation from the radioactivity analysis of lime and cement used in Bangladesh

The radioactivity concentrations of 232Th, 226Ra, 40K and 137Cs were measured using high-resolution γ-ray spectrometry in limestone, powdered lime, by-product lime and cement used in Bangladesh. The activity concentrations, Ra equivalent activities, representative level index values for all samples and the effective dose equivalents due to the intake of the above-mentioned radionuclides in limestone and powdered lime by the adult group were estimated. The mean activity concentrations of 232Th, 226Ra and 40K were 60.8, 60.2 and 928 Bq kg -1, respectively for limestone, 107, 68.0 and 1660 Bq kg -1, respectively, for powdered lime and 83.0, 31.0 and 972 Bq kg -1, respectively, for by-product lime. For cement, the mean activity concentrations of 232Th, 226Ra and 40K were observed to be 54.3, 29.7 and 523 Bq kg -1, respectively. The presence of 137Cs was not detectable in any of the studied samples. The measured average activities of 232Th, 226Ra and 40K for all samples were relatively higher than the world typical values except for 226Ra in cement and by-product lime. The calculated mean Ra equivalent values for limestone, powdered lime, by-product lime and cement were 219, 349, 224 and 148 Bq kg -1, respectively. The corresponding representative level index values were found to be 1.63, 2.63, 1.68 and 1.09, respectively. The mean effective dose equivalent values of 232Th, 226Ra and 40K for limestone were 56.5×10 -7, 41.6×10 -8 and 50.8×10 -10 Sv g -1, respectively, and those for powdered lime were 99.5×10 -7, 46.9×10 -8 and 91.3×10 -10 Sv g -1, respectively.

A high temperature and high sensitivity micro-thermobalance

A thermobalance which ensures a sensivity of 1 × 10 −6 g and an excellent stability up to 1500 C has been developed. A sample, which is suspended from one end of the beam of the balance, is heated in a compact furnace with a small heat capacity. Temperature is measured by a Pt-PtRh (10%) thermocouple placed close to the sample. Use of an alumina mantle ensures easy control of atmosphere: at room temperature, the evacuation can be done to 1 × 10 −4 Torr, and stable operation can be done up to 1500 C in air inert gas at a flow-rate smaller than 50 ml min −1. It is also possible to use a corrosive gas as atmosphere. In a blank test with platinum cell support (6.5 mm diam. and 0.1 mm thick) suspended in an air stream of 50 ml min −1 and heated up to 1500 C at 10 C min −1, the drift was smaller than 20 × 10 −6 g and the reproducibility was better than 10×10 −6 g. This paper refers to the construction of the thermobalance, and its performances. And some examples of high temperature thermogravimetry through the results of analyses of CaCO 3, quick lime and byproduct lime are also reported.