Relationships between Application Amount of Quicklime and Soil Nutrients,Flue-cured Tobacco Quality in Panzhihua City

[Objective] This study aimed to investigate the improving effect of quick- lime on acid soil in tobacco-growing areas in Panzhihua City. [Method] The effects of four application amounts （450, 900, 1 350 and 1 800 kg/hm2） of quicklime on soil nutrients and flue-cured tobacco quality were observed for two consecutive years. [Result] In acid soil, the application of quicklime significantly improved soil pH. In addition, it showed significant effects on soil nutrients, flue-cured tobacco quality, tobacco output and tobacco leaf chemical components. When the application amount of quicklime was increased to 1 350 kg/hm2, the improving effect of quick- lime on soil nutrients was best, the flue-cured tobacco yield and quality all reached the highest, and the chemical components of tobacco leaves were closest to the in- herent indicators of high-quality tobacco leaves. [Conclusion] This study will provide certain reference for accurate application of quicklime in tobacco-growing area in Panzhihua City.

Study on Performance Regulation and Mechanism of Quicklime and Biopolymer on Hemihydrate Phosphogypsum

In order to reduce the influence of impurities in hemihydrate phosphogypsum(HPG)on the environment and improve the workability of HPG,the effects of the content of quicklime and types of biopolymer(hydroxypropyl methylcellulose,xanthan gum,sodium polyacrylate(PAANa))on the compressive strength,softening coefficient and ultrasonic velocity of HPG were evaluated.When the content of quicklime was 1.5%and the content of PAA-Na was 0.2%,HPG had the best mechanical properties and workability,its water retention rate can be increased by 5.8%,and unconfined compressive strength of 3 days increased by 10.3%and 7 days increased by 13.1%.Through the analysis of scanning electron microscope and X-ray diffraction,it was found that the hydration reac-tion of HPG was more sufficient,the pores size and number decreased,the number of impurities on the crystal surface decreased obviously,and CaF2 and other substances were formed by the reaction after the addition of quicklime.After adding quicklime and PAANa,the indicators of gypsum self-leveling mortar prepared by HPG meet the requirements of the standard.

Production of Bio-Calcium Oxide Derived from Hatchery Eggshell Waste Using an Industrial-Scale Car Bottom Furnace

The valorization of eggshell waste as bio-calcium oxide is crucial for pollution prevention and supporting sustainable development.There are several reports on the thermal conversion of eggshell waste to calcium oxide for the partial or complete substitution of natural lime applications.However,this paper reports the thermal decomposition of large amounts of hatchery eggshell waste on an industrial-scale car bottom furnace for the first time.The hatchery eggshell waste was sundried and placed into five stacked trays in the car bottom furnace.The calcination of the eggshell waste was conducted at 900℃ for 3 and 4 h under an atmosphere of air.Both the physical and chemical properties of the eggshell samples and the bio-quicklime products were carefully examined by TGA,SEM,XRD,FTIR,and XRF.The results demonstrate that the purity of calcium oxide in the quicklime products increased from 79%to 87%upon increasing the calcination time from 3 to 4 h.However,the color of the calcined eggshell samples at the surface of the pile was white while the color of the product beneath the surface was black or dark gray.The purity of the calcium oxide of both the black and white calcined samples was 76.4%and 91.5%,respectively.These results indicate the limited efficacy of the car bottom furnace for thermal decomposition of the large amount of eggshell waste to calcium oxide.Additionally,the production cost of bio-calcium oxide is approximately twice the cost of industrial grade lime.For further industrial applications,the furnace should contain the mixing equipment for improving the thermal decomposition of the large pile of eggshell waste.Furthermore,the oil burner system may be used in order to reduce fuel costs.

Research on Characteristic of Fe²⁺/S₂O^2-<sub style="margin-left:-7px;">8</sub>Composite CaO Synergetic Conditioning for Municipal Sludge

For the problem as high energy consumption and sludge increment during the municipal sludge management process with advanced oxidation technology of sulfate radical, the Fe2+/S2O2-8 composite CaO reaction system was set up. Meanwhile, systematical studies had been carried out for coordinated conditioning of municipal concentrated sludge. The scientific process parameters were determined with the help of sludge capillary suction time, sewage sludge moisture content and other core indicators and the effect of traditional polyacrylamide flocculation method, Fenton method and activated persulfate method were compared. The results showed that in the neutral concentrated sludge conditioning, there were outstanding advantages for Fe2+/S2O2-8 composite CaO reaction system compared with Fenton, CPAM, and SO-4 methods and the optimal parameters for dosage were as follows: Fe2+/S2O2-8: 80 - 120 mg·g-1 DS, n(Fe2+):n(SPS) = 0.8:1, CaO: 200 mg·g-1 DS. To achieve similar performance index, the dosage of Fe2+ per ton for sludge could be reduced by 20%, the loss rate for iron in filtrate was 0.5%, dewatering of sludge by suction filtration was within 50 s and the moisture content for dewatering cake was 53.7%, which significantly improved the economy and practicability of SO-4 advanced oxidation technology, and the results were expected to form a useful supplement to the popularization and application of SO-4 advanced oxidation technology.

Recycling of Ornamental Stones Hazardous Wastes

Sawing and polishing of the ornamental stones always generate large amount of solid and wet hazardous wastes, which pollute the environment. In Shak Al-Thoaban area, East Cairo, Egypt, huge amounts of these wastes were accumulated, during the last years, as rejects “Solid” and wet “Sahala” wastes, representing one of the main sources of environmental pollution. The aim of this work is to characterize and evaluate these wastes for recycling in quicklime production. Hence, samples of both wastes were investigated for their chemical and mineral composition applying XRF, XRD, DTA and TGA methods. Free lime content and reactivity (RDIN) of both samples were also determined after calcination for differnt soaking times (0.25 - 2.0 hrs) at 1000℃. The results were interpreted in relation to composition and microstructure of the fired samples as revealed by TLM and SEM methods. The RDIN reactivity of the resulted lime is changeable along soaking time at 1000℃because of the microfabric of its crystallites. The lime of the “Solid” sample is preserving the original limestone microstructure that contributes in its higher RDIN reactivity values at all soaking times. The relatively higher degree of grain growth of lime crystallites in the “Sahala” sample leads to its lower reactivity. The optimum soaking times for the highest lime reactivity are 0.25 and 1 hr. for the “Solid” and “Sahala” samples, respectively. On increasing soaking time up to 2 hrs, both samples show minimum RDIN values. The “Solid” sample also gives higher free lime content than the “Sahala” one at all soaking times. It is gradually increased in the former sample up to a maximum (96% - 97%) on increasing soaking time up to 1-2hrs. On the other side, a maximum free lime (~95%) is detected in “Sahala” sample at 0.25hr soaking time and gradually decreased to (87%) up to 2hrs.

Effect of relative humidity on the desulfurization performance of calcium-based desulfurizer

Low desulfurization efficiency impedes the wide application of dry desulfurization technology,which is a low-cost and simple process,and one significant solution is the development and manufacture of high-performance desulfurizers.In this study,firstly,a steam jet mill was used to digest quicklime;then,we utilized numerical simulation to study the flow field distribution and analyze the driving factors of quicklime digestion;and lastly,the desulfurization performance of the desulfurizer was evaluated under different relative humidities.The results show that the desulfurizer prepared via the steam jet mill had better apparent activity than traditional desulfurizers.Also,the entire jet flow field of the steam jet mill is in a supersonic and highly turbulent flow state,with high crushing intensity and good particle acceleration performance.Sufficient contact with the nascent surface maximizes the formation of slaked lime.The experiments demonstrated that the operating time with 100%desulfurization efficiency and the“break-through”time for the desulfurizer prepared via the steam jet mill is longer than that of traditional desulfurizers,and has significant advantages,especially at low flue gas relative humidity.Compared with traditional desulfurizers,the desulfurizer prepared via steam jet mill expands the range of acceptable flue gas temperature,and the failure temperature is 1.625 times that of traditional desulfurizers.This work breaks through the technical bottleneck of low dry desulfurization efficiency,which is an important step in pushing forward the application of dry desulfurization.

Hydrophobicity and carbonation treatment of earthen monuments in humid weather condition

Water stability of soil is crucial to the durability of earthen monuments,especially those located in the humid weather condition.This paper discusses the selection reason of materials(tung oil and quicklime) for earthen monument treatment,and then validates the applicability of these materials with tests of soil-water characteristic curve(SWCC),aggregate stability test(AST) and scanning electron microscope(SEM).The soil tested was sampled from Da Bao'en temple in Nanjing,Jiangsu province,China.The test results indicate that the carbonation reaction of quicklime offers a favorable environment for the formation of tung oil film.Meanwhile,the regulatory function of tung oil restricts the crystallinity of calcium carbonate(CaCO3) and forms fine crystals.Soil treated with both of tung oil and quicklime has good water repellency and aggregate stability without obvious changing in aesthetic appearance.Hydrophobicity and carbonation treatment can be applied prospectively in the conservation of earthen monument located in humid weather condition.