Amount Of Limestone Research Articles

Using dolomitic limestone to replace conventional alkalinization in the biodigestion of rapid acidification cassava processing wastewater

Anaerobic digestion (AD) of rapid acidification wastewaters (RAW) in high-rate reactors is highly dependent on properly controlling the buffer capacity of systems, which is usually done by dosing alkalizing/alkali compounds. Although reliable, this strategy does not ensure complete effectiveness, depending on the chemical used, also affecting negatively the economic performance of the treatment plants. The aim of this study was to assess an alternative approach to conventional alkalizination in the AD of RAW by using dolomitic limestone as the alkalizing agent in single-phase continuous systems fed with cassava processing wastewater (CPWW). Two different amounts of limestone were used in horizontal-flow reactors subjected to increasing organic loading rates (OLRs). The effects of dolomite on the specific methanogenic activity (SMA) of the methanogenic sludge, as well as the fertilizer potential of the treated CPWW were also assessed. Limestone supplementation positively affected the SMA of the sludge by increasing methane production and decreasing the lag phase. Limestone also proved to be an adequate alkalizing agent for the horizontal-flow systems, continuously providing the systems with bicarbonate alkalinity at relatively high OLRs (up to 8.5 kg COD m−3 d−1), even during organic overloading periods. The availability of specific inorganic constituents, primarily K+, Ca2+ and Mg2+, also confirmed the biofertilizer potential of the treated CPWW, although higher organic matter removal levels would still be required for safer nutrient cycling.

Effect of slag basicity in ferromanganese production using medium-grade manganese ore from East Java-Indonesia

ABSTRACTFerromanganese is one of the most important alloying elements in steel industries. In this work, the production of ferromanganese was carried out using three-phase submerged mini electric arc furnace. The effect of slag basicity due to the addition of a various amount of limestone as fluxing agent on this smelting process was investigated. The chemical composition of ferromanganese and slag was analysed with X-ray fluorescence. From this experiment, the optimum slag basicity was 0.8 that produced 8.2 kg of ferromanganese with 78.1% Mn, 12.7% Fe, and 8.9% Si. It resulted from 30 kg of manganese ore, 7.5 kg of cokes, and 12 kg of limestone.

Effect of Curing Regime on the Properties of Alkali-Activated Slag/Limestone Mortar Subjected to High Temperatures

Alkali-activated slag has a higher resistance against exposure to high temperature compared to ordinary Portland cement concrete. Nevertheless, its mechanical properties are also deteriorated due to partial decomposition of the C-A-S-H matrix. This paper investigates the effect of various curing regimes applied to the samples which were exposed to temperature 200–1200 °C on the mechanical properties and microstructure of the alkali-activated slag/limestone blends. The amount of limestone was 15% from the mass of slag. On set of specimens was treated on air at laboratory conditions, the second set was immersed in water and the last was treated stored in humid chamber with 95% relative humidity for the period of 60 days. The results showed that water curing has a strong positive influence on the compressive as well as flexural strength of the specimens exposed to temperatures up to 600 °C. Specimens which were exposed to 800 and 1000 °C showed the best performance after treatment in humid chamber, and after exposure to 1200 °C the best compressive strength exhibited the air cured samples.

Effect of limestone powder as a partial replacement of crushed quarry sand on properties of self-compacting repair mortars

Self-compacting repair mortars (SCRM) are particularly desired for the rehabilitation and repair of reinforced concrete structures. The properties of SCRM can be improved by using chemical, mineral, polymer and fiber additives. In limestone quarries, considerable quantities of limestone fine powder are obtained during the process of crushing rock. These fine powders are being collected and their utilization is a big problem from the aspects of disposal, environmental pollution and health hazards. The introduction of limestone powder as cement and sand replacement present interesting possibilities to reduce the cement cost production, CO2 emission and the conservation of natural resources. The effects of limestone powder content in crushed sand on the properties of SCRM are not studied. An experimental study was undertaken to find out the effect of limestone powder content on fresh and hardened properties of SCRM. SCRM mixtures were prepared using crushed sand partially replaced with limestone powder at varying percentages up to 30%. Results indicate that the limestone powder as sand replacement significantly improves the fresh and hardened properties of SCRM with a content ranging from 10 to 15%. The use of limestone powder in repair mortar and concrete application would offer technical, economical and environmental advantages for concrete producers.

Americhem buys Vi-Chem

The lignin (L) precipitated from black liquor was mixed with eggshell (ES) and followed by carbonization to prepare a hybrid porous adsorbent. The performance of removing of trace sulphur dioxide (SO2) from the air at room temperature was investigated. The optimization and statistical work was conducted by using the central composite design (CCD) together with the response surface methodology (RSM). Among the investigated operational parameters, the effect of carbonization temperature was found to be the most significant to the performance of SO2 removal by the prepared hybrid adsorbent. With an increase of carbonization temperature, the specific surface area increased appreciably reaching 130 m2.g−1 at 800 °C (L-ES-50-800-50). XRD analysis indicates the crystallite phase transition from calcite (CaCO3) to limestone (CaO) with an increase of carbonization temperature. The FT-IR study indicates the disappearance of out-plane vibration peaks of C-O from CaCO3 and gradual appearance of peaks from Ca-O of limestone on the surface of prepared hybrid material as an increase of carbonization temperature. The increased specific surface area and amount of limestone in the prepared hybrid adsorbent are found to contribute to the increased SO2 removal by the prepared hybrid adsorbent. The final optimal preparation condition was determined using RSM by setting maximum SO2 removal performance as optimization goal. The optimal preparation conditions achieved were: 50% = L/(L + ES), carbonized at 800 °C for the duration of 50 min. The prepared hybrid adsorbent at the optimal preparation condition showed excellent SO2 removal performances in both wet and dry conditions.

Effect of limestone powder as a partial replacement of crushed quarry sand on properties of self-compacting repair mortars

Self-compacting repair mortars (SCRM) are particularly desired for the rehabilitation and repair of reinforced concrete structures. The properties of SCRM can be improved by using chemical, mineral, polymer and fiber additives. In limestone quarries, considerable quantities of limestone fine powder are obtained during the process of crushing rock. These fine powders are being collected and their utilization is a big problem from the aspects of disposal, environmental pollution and health hazards. The introduction of limestone powder as cement and sand replacement present interesting possibilities to reduce the cement cost production, CO2 emission and the conservation of natural resources. The effects of limestone powder content in crushed sand on the properties of SCRM are not studied. An experimental study was undertaken to find out the effect of limestone powder content on fresh and hardened properties of SCRM. SCRM mixtures were prepared using crushed sand partially replaced with limestone powder at varying percentages up to 30%. Results indicate that the limestone powder as sand replacement significantly improves the fresh and hardened properties of SCRM with a content ranging from 10 to 15%. The use of limestone powder in repair mortar and concrete application would offer technical, economical and environmental advantages for concrete producers.

Pennsylvanian Stratigraphy of Douglas County, Kansas: Glacioeustatically Modulated Cyclic Deposition on a Remarkably Smooth Shelf

The Middle and Late Pennsylvanian succession of Kansas consists of two types of cyclothems, lithologic successions that consist of several members that repeat in a particular order. Cyclothems are a few meters to a few tens of meters thick. One type of cyclothem, the Kansas cyclothem, or here the limestone-rich cyclothem, consists of interbeds of limestone and shale, where the amounts of limestone are approximately equal to the amount of shale or dominate the succession. This trip will study one such cyclothem in the Oread Limestone at Stop 3 and possibly another cyclothem at the optional Stop 4. Siliciclastic cyclothems are dominated by shale and may contain an incised valley filled partly by fluvial or estuarine sandstone. The Lawrence Shale, which we will see at Stops 2 and 3, contains such features. While many cyclothems are incomplete, both types of cyclothem may contain dark gray to black, fissile, phosphatic core shale beds, commonly a meter or less thick, and an underlying transgressive deposit beneath. Overlying deposits represent regression or progradation of the shoreline: either lime mudstone grading to grainstone or clay-rich marine shale grading to coarse siltstone or fine sandstone. Paleosols and fossils of marine invertebrates are common and indicate that deposition took place in both marine and non-marine conditions. Some marine deposits show a paleosol overprint. The deposits indicate that the area was a shelf during the Late Pennsylvanian where relief was very low, and very laterally extensive deposits formed as sea level rose and fell. The alternation of shale-rich and limestone-rich intervals plus the feet-per-mile dip to the WNW create the characteristic topographic expression of cuestas with gently sloping caps that are underlain by limestone. While glacial deposits are mostly restricted to northern and east-central Douglas County, Pleistocene glaciers influenced the erosional and drainage patterns of the area.

Limestone quarry production planning for consistent supply of raw materials to cement plant: A case study from Indian cement industry with a captive quarry

A long term production planning of limestone quarry is presented to supply consistent quantity and quality of limestone to a cement plant. A case study from Indian cement industry is presented where the cement plant has a captive limestone quarry. The objectives of this study are: (a) to investigate how long the limestone quarry can alone supply the desire quality and quantity materials to the cement plant; and (b) to investigated the possibility of extending the quarry life by utilizing some quantity of the limestone from the different source and blending that limestone with the limestone from the quarry to achieve the target quality and quantity of the cement plant. These objectives are achieved by generating the production sequencing of the mining blocks using a sequential branch-and-cut algorithm. The results revealed that up to 15 years, the existing quarry alone can serve the cement plant. If certain quantity of limestone can be brought from the other sources, the life of the study quarry is significantly improved. The life of the quarry increased from 15 years to 85 years. The study also helps to calculate the desire quality of the limestone that will be brought from other sources throughout the life of the quarry.

Lignite-Fired CFB Boiler SO<sub>2</sub>, NO Emission Control Technology Research

For study on SO2 and NO emission characteristics of circulating fluidized bed boiler experiments were carried out in a 300MW circulating fluidized bed boiler. In these experiments, the variables were the amount of limestone and bed temperature. While conducting the test, the reasons for the changes in emission were analyzed, and some advices about combustion adjustment were proposed.

Bench-Scale Preparation and Qualitative Analysis of Calcium Chloride from Locally Available Raw Materials

Calcium chloride has diverse industrial applications. In spite of its demand and availability of raw materials locally, there are no chemical industries in Bangladesh that produce calcium chloride as a major product. This work was undertaken to assess the feasibility of production of calcium chloride on bench-scale by limestone-hydrochloric acid process and the quality of the product. Different amounts of limestone and 35.5% hydrochloric acid (by weight) were reacted in a PVC reactor to produce calcium chloride. Solubility at different temperature, pH, and calcium content were among the parameters measured to assess the product quality. FTIR Spectroscopy was also conducted to determine the quality of the product. Solubility values of the product ranged between 96-155g/100g water for temperatures between 30-100°C; calcium content of the product was found to be 25%. DOI: http://dx.doi.org/10.3329/jce.v28i1.18101 Journal of Chemical Engineering, Vol. 28, No. 1, December 2013: 1-3

시멘트 생산과정에 따른 CaO 함량과 CO2의 발생량

In this study, contents of limestone in cement manufactured by six domestic plants for Portland cement were investigated in terms of the strength and its relation to the CO2 emission due to limestone material and its physical properties in cement manufacturing process. the relationship among CaO content, compressive strength, and CO2 emission was surveyed for the limestone quantity in decomposition reaction and the loss of limestone quantity contained in each cement. As a result of CO2 emission calculation for unit cement, it was found that the CO2 emission due to decomposition of limestone was occupied 67% of total emission quantity. Furthermore, there was a difference in CO2 emission quantity depending on the cement manufacturing process management. Also, it was shown that fossil fuel usage and material loss had a major influence as main factors of CO2 emission. An increase in the CaO content in cement resulted in an increase in the compressive strength. On the contrary, CaO content and compressive strength were reduced with the growth of loss quantity of limestone. It was verified that the material and process management were more effective than CaO yield in cement manufacturing for CO2 emission with the growth of CO2 emission quantity. Pozzolanic materials such as PFA and GGBS in concrete mix affected the price, CO2 emission and development of strength

Management of melting process of electrical furnaces in Drenas

The weight of the load is one of the main parameters in reductive melting process in electrical furnace which depends on the roasting of ores in a furnace located in Drenas. Roasting of the load is done at ∼950°C, which is composed of ores from Drenas and Albania. Also, the article has the experimental analyses that modify some parameters of the production which are the reduction in quantity of limestone in the load and the increase in quantity of quartz used in the load. The paper emphasises the possibility of mixing the ore from Kosovo with the lateritic ore from Albania with the aim of reducing the acidity of weight which is loaded in the electrical furnace. The optimisation of the above mentioned parameters enhances the production process and provides better practical results. The composition of the load must satisfy the ratio 1∶10 of ore from Kosovo and Albania to optimise the melting process.

A study on the calcination and sulphation behaviour of limestone during oxy-fuel combustion

The mechanisms governing the behaviour of limestone for in-furnace desulphurisation during oxy-fuel combustion have been investigated in this paper. Apart from the use of pure limestone, the mixtures of limestone with a brown coal (i.e., lignite) at different mass ratios have also been examined to address the influence of ash on the behaviour of limestone. The combustion experiments were conducted in a drop-tube furnace at a furnace temperature of 1273K and a reactor length of 1200mm for a nominal particle residence time of approximately 1.0s. Pure air and an O2/CO2 mixture at a volume ratio of 27:73 were tested. SO2 at a concentration of 1000ppm was also doped into these two gases to examine its competition with Si and Al in the ash on the interaction with limestone. A high CO2 partial pressure has been confirmed to slow down the calcination of limestone in O2/CO2. However, mixing limestone with coal enhanced the limestone calcination by increasing the particle temperature through radiative heat transfer from flame. With a large quantity of limestone such as the 18% tested here, direct sulphation is a major route contributing to sulphur capture during oxy-fuel combustion. The importance of direct sulphation is exceeded by indirect sulphation via an initial calcination of limestone when medium and low quantities of limestone are added to coal. The Si and Al in coal undermine the calcination and sulphation of limestone in O2/CO2 because of the preferential formation of Ca aluminosilicate eutectics. These eutectics tend to melt and deposit on the unreacted limestone surface, thus providing extra resistance to the diffusion of gas through the limestone particles. Increase of SO2 content in flue gas favours the indirect sulphation of calcium over the interaction of calcium with ash, thereby increasing the extent of desulphurisation during oxy-fuel combustion.

Application of Desulfurization Additive in Desulphurization System for 600MW Units

This paper studies the application of desulfurization additives in the desulfurization system for 600MW units, Results show that desulfurization additives have a positive effect on the desulphurization efficiency, and it can gain notable economic benefits when it guarantees the effective concentration of the desulfurization additives and the quantity of limestone

Available phosphorus levels in diets for 30 to 60 kg female pigs selected for meat deposition by maintaining calcium and available phosphorus ratio

With the objective to evaluate levels of available phosphorus (aP) in diets for pigs selected for meat deposition by maintaining the calcium and available phosphorus ratio, it was used 50 commercial hybrid female pigs with initial weight of 30.32 ± 0.29 kg, distributed in a complete randomized experimental design, with five treatments, five replicates, and two animals per experimental unit. Treatments were composed of a corn-soybean meal basal diet and four diets obtained by supplementation of basal diet with dicalcium phosphate, resulting in diets with 0.144; 0.224; 0.304; 0.384 and 0.464% of aP. Calcium levels were adjusted by varying the quantities of limestone in the diets. There was no effect of aP on both daily feed intake and feed conversion. Levels of aP affected daily weight gain which increased quadratically up to the estimated level of 0.372%. There was no effect of aP on quantity of phosphorus in the bones. The quantity of calcium in the bones and percentage of ash in the bones were influenced in an increasing linear way by the aP in the rations. The best result of weight gain of swine females, from 30 to 60 kg, genetically selected for meat deposition, is provided by the level of available phosphorus of 0.372%, which corresponds to a relationship with calcium of 2.06:1 and to a daily intake of 8.20 g of available phosphorus.

Experimental Investigation of Hydrogen Chlorine Bonding with Limestone and Dolomite in the Furnace of a Stoker-Fired Boiler

The paper presents results of experimental semi-technical investigations to limit the mobility of chlorine released in the form of hydrogen chloride from the fuel in the stoker-fired boiler furnace. In the combustion process, limestone and dolomite were used as the sorbents. The background for the research was a fuel containing a low gram fraction of chlorine, namely, extracted rapeseed meal supplemented with polyvinyl chloride (PVC) recyclate granules, to diversify the quantity of the quick-release chlorine. The research results indicate the tendency ofchanges of the hydrogen chloride concentration in the flue gas in relation to the amount of PVC added to the fuel, i.e., gram fraction of chlorine, amount of limestone and dolomite added to the fuel, as well as the molar ratio Ca/Cl 2 or (Ca + Mg)/Cl 2 , respectively. It has been proven that the greatest dechlorination capacity is exhibited by hydrated lime, lesser by limestone, and the least by dolomite, which, nonetheless, can be used under certain conditions for HCl bonding in boiler furnaces.

Model of fragmentation of limestone particles during thermal shock and calcination in fluidised beds

Fragmentation of limestone due to thermal shock and calcination in a fluidised bed was studied through experiments and modelling. The time for heating was estimated by model calculations and the time for calcination by measurements. Fragmentation due to thermal shock was carried out by experiments in a CO 2 atmosphere in order to prevent the effect of calcination. It was found to be much less than fragmentation due to calcination. Average particle sizes before and after fragmentation are presented for several types of limestone. The effects of particle size and gas composition on the primary fragmentation were studied through experiments. Increasing the fluidisation velocity increased the tendency to fragment. The evolution of the particle size distribution (PSD) of limestone particles due to thermal shock and during calcination (or simultaneous calcination and sulphation) were calculated using a population balance model. Fragmentation due to thermal shock is treated as an instantaneous process. The fragmentation frequency during calcination is presented as exponentially decaying over time. In addition to the final PSD, this model also predicts the PSD during the calcination process. The fragmentation was practically found to end after 10 min. Furthermore, a population balance method to calculate the particle size distribution and amount of limestone in fluidised beds in dynamic and steady state, when feeding history is known, is presented.

Treatment of acidic water from Bekok River using open limestone channel

Bekok River is one of the raw water resources for Batu Pahat treatment plants which supply treated water for domestic, institutional, commercial and industrial use. Due to soil characteristics and agricultural activities in the catchment area, pH of lower than 5.5 is common to the river, particularly in the stretch where the water intake point is located. However, at times, Bekok River registered low pH of less than 3.5 and hence caused problems to the treatment plants. The cost to neutralise the water increased and treatment scheduling became more complicated. A preliminary laboratory scale study has been conducted to determine the viability of using an open limestone channel as an in-situ pH treatment in the river. Two sets of experiments using synthetic and actual raw waters with various sizes and amount of limestone were carried out. Results indicate the viability of the process. Depending on the initial pH and acidity of the raw water, the pH can rise to 6.0 within 30 minutes of contact time. The amount and size of limestone was found to play an important role in minimising the contact time.

露天資源開発の現状と新たな展開を支える技術 環境と調和し，人に優しい石灰石鉱山の開発―戸高鉱山：神野・八戸鉱区の開発―

Tsukumi is the greatest limestone supply region in Japan , and five companies are quarrying 30 million tons every year in this area. TODAKA MINE of TODAKA MINING CO. which is one of them is located in the west of this area , and is now quarrying 12 million per year . The total amount of limestone produced so far is to 370 million-tonnes since commencement . However , the remaining quantity of limestone that can be excavated had decreased . Development of a new mine is planned in Usuki, next to Tsukumi .It was decided that this new quarry, conceived in the 21st century, should be designed and developed to a corporate philosophy which values the well-being of local residents and their environment. The quarry project is designed to have a production capacity of 12 million tones per year, to be welcomed by the local community, and to secure the supply of limestone for future generations.

環境と調和し，人に優しい２１世紀型石灰石鉱山の開発

Tsukumi is the greatest limestone supply region in Japan, and five companies are quarrying 30 million tons per year in this area. TODAKA MINE of TODAKA MINING CO, which is one of them is located in the west of this area, and is now quarrying 12 million per year . The total amount of limestone produced so far is to 370 million tons since commencement . However, the remaining quantity of limestone that can be won had decreased . In order to keep the stable limestone supply, development of a new mine is planned in Usuki, next to Tsukumi .It was decided that this new quarry, conceived in the 21st century, should be designed and developed to a corporate philosophy which values the well-being of local residents and their surroundings. The quarry project is designed to have a production capacity of 12 million tons per year, to be welcomed by the local community, and to secure the supply of limestone for future generations.