The paper is concerned with the hydrogeological appraisal of the proposed mining operations in the Thar Lignite field in Sindh, Pakistan. The Thar coalfield covers an area of approximately 9000km2 and contains three Lignite seams lying at depth of 130m to 250 m. In the Thar Lignite field, the presence of three main aquifers induces pore pressure in the rock mass surrounding the Lignite seams and makes high wall slopes potentially unsafe. It is, therefore, necessary to dewater the rock mass before commencing mining excavations. The paper describes the proposed mine dewatering scheme to facilitate depressurising of the rock mass surrounding the mining excavations. Inflow prediction of groundwater to the surface mining excavation was carried out using a SEEP/W finite element software package. The simulation results show that the ground water inflow from the Top aquifer is 114m3/d, from the Intermediate confined aquifer is 141m3/d and from the Bottom confined aquifer is 1.28´105 m3 /d. These results were compared with the analytical solutions which indicated that the relative error of estimation of inflow quantities varies from 3.4 % to 6.4%.

Although today’, s fossil fuel reserves have been still considered a long-term energy supply, biomass has received worldwide attention as a cheap and renewable energy source due to the known global environmental impact of fossil fuel usage. Then co-processing of fossil fuels and biomasses to produce substitute liquid fuels is one option to appraise fossil fuel reserves for the economy. In this work, pyrolysis of Soma Lignite and an oil plant cake, and their blends of varied proportions in the form of pellets were studied to elucidate the main differences between the behavior of these materials and their blends during fast thermal decomposition carried to convert their valuable products. A special vertical heating chamber, which enabled very fast heating, was used in the experiments conducted at 500-700oC temperature range. The results showed that these two materials mutually interacted when the cake ratios of the pellets were below 50%. For blends with 75% cake, some interaction was observed only at 700oC. It is concluded that the interaction between two materials during pyrolysis is affected by the outflow rates of volatiles into the sweeping gas. Maximum liquid yields corresponded to blends containing OPC greater than 75%.

Lignite has emerged as an additional important fuel source for thermal power generation in India. Circulating fluid bed combustion technology is applied considering the impurities, moisture, ash and sulfur content, and wide variations for large units. Lignite mineralogy greatly influences combustion behavior. Agglomeration and clogging/blockage are experienced due to sintering of Lignite at lower temperature regime in which circulating fluid bed boilers operate (800oC to 900oC). At this low temperature range, the extensive knowledge built for pulverized coal combustion with respect to slagging, fouling, and high-temperature corrosion is not useful. Sintering studies using the heating microscope's potential are applied for understanding this phenomenon. The gray clay, which occurs as intrusions/thin bands in the Lignite mine, is sampled at the mine site and taken up for analysis. Morphology of sintered deposits in the bottom ash is matched with the properties of clay which is very close to halloysite mineral (kaolinite group). Sintering is avoided by selecting the operating temperature range of combustion on either side of peak sintering temperature in the sample case. With higher ashing temperature, the Lignite ash loses part of its sintering tendency. This indicates to a new hypothesis that once the Lignite ash undergoes transformations resulting in sintering, its sintering tendency is lowered. Conventional slagging indices are also analyzed, and correlation was derived for sintering behavior of Lignite.

Ground water and surface water create a range of problems in Lignite mining utilizing surface mining methods. In order to create a safe and economic mining environment, it is essential to carry out mining after dewatering the rock mass surrounding the Lignite mines by advance dewatering techniques. This paper briefly describes the ground water regimes including pressure gradients associated with various Lignite deposits together with the practical examples of some important Lignite deposits in the world. An effective method of controlling ground water in multi-aquifer environment in Lignite deposits is to carry out rock mass dewatering using borehole pumps. This approach will help reducing the inflow rates of ground water to the mining excavation and also increase the effective strength of the overburden strata, thus, increasing the slope stability of the mining excavations. The main theme of this paper is to present a case history analysis of Thar Lignite deposit in Sindh, Pakistan which has Lignite reserves of some 193 billion tonnes. The paper presents a proposed method of dewatering the Thar prospect together with an assessment of the quality of aquifer water which can be used to improve the quality of life of people inhabiting in the Thar Desert area of Sindh, Pakistan.Water samples from three aquifers were collected from nine different locations and were analyzed in the laboratory for evaluating their physical and chemical characteristics. The test results indicated that the aquifer water can be classified as (sodium+ potassium) -chloride type water with a TDS range of 1000 to 20,000 mg/L. Consequently, this ground water is classified as brackish (saline water) requiring treatment before it can be utilised for domestic or industrial consumptions. It should be noted that this ground water does not contain heavy metals and toxic metals including arsenic, mercury and lead or cyanide. However, results indicate that groundwater from a few locations contained traces of silver (<4oppb) Owithozinc0<0.1ppm.

The aim of this research was to produce a convenient additive for enhancing the properties, especially the fluid loss, of oil well cement slurries. In this regard, a variety of drilling/cementing chemical additives known as fluid loss controllers were prepared through derivatization and chemical modification of Lignite. Lignite-based graft copolymers were synthesized using different groups of acrylic monomers via aqueous the free radical polymerization method. Then, it was allowed to react with sulfomethylating agents to enhance its water solubility. Subsequently, a comparative sulfomethylated Lignite was prepared and employed as the backbone in the free radical polymerization. ATR-FTIR and elemental analyses were performed to demonstrate the structures of the fluid loss controller and incorporated elements. The performance of these additives in improving the properties of oil well cement slurries was investigated through analyzing the quality of fluid loss controller in saline saturated slurries. Under similar desired well conditions, i. e. a compressive strength of 800-1100 psi, a thickening time of 400 minutes, and a viscosity of 25 cP, a fluid loss below 130 ml API was obtained. The best standard performance was assigned to the cement slurry which employed sulfomethylated Lignite graft copolymer.

Most of rangeland soils are limited in their ability to supply adequate nutrients to plants. Soil conditioners have shown to alter soil fertility and plant characteristics. This investigation aims to evaluate the influence of two soil conditioners on nutrition value of N. schoberi and A. podolobus. For this, two separate experiments for each species were carried out in a greenhouse using a completely randomized design with three replications during 2018 and 2019. Treatments had four levels of Wheat Straw Biochar (WSB) as well as Lignite at rates of 0, 1. 25%. 2. 5% and 3. 75% w/w added to clay loam soil. In the end of vegetative stage and before flowering, plant samples were taken and their Crude Protein (CP) and Acid Detergent Fiber (ADF) content were measured and then, Dry Matter Digestibility (DMD) and Metabolizable Energy (ME) were calculated. Data were analyzed by One-way analysis of variance (ANOVA) and the means were compared using Duncan's test. The results demonstrated that WSB addition had no effect on nutrition value of both species. By application of Lignite, CP content of N. schoberi enhanced up to 44. 45% more than that for control. The effect of Lignite addition on nutrition value traits was high for N. schoberi. But this material had no effect on A. podolobus quality traits. Based on our findings, application of Lignite at 3. 75 (w/w) was recommended to improve soils of rangeland for cultivation of N. schoberi in dry-land plantation projects or the conversion of dry lands to arable pastures.

: In this work, solid-phase nitro-humification process was developed to activation of lignitic nitro-humic substances (NHSs) by using the two-step sequential treatment assisted by nitrogen enrichment (using KOH and urea as a humic acid activator and a nitrogen enrichment agent, respectively) and ozone oxidation in fixed-bed reactor. The changes in main elements, spectral index of humification (E4/E6), surface functionalization, and textural properties were determined by CHNOS analysis, ultraviolet-visible (UV-VIS), Fourier-transform infrared (FT-IR) spectroscopy, and specific surface area (SSA) analysis based on BET, BJH and t-plot models, respectively. The results revealed the increasing 2.25 and 2.94-folds on the yield of alkali and water-soluble NHSs, respectively, compared to the conventional alkaline extraction method. A 14.5% reduction in the carbon content owing to ozone oxidation and 8.15% nitrogen enrichment resulting from urea pretreatment led to an ideal humification ratio (C/N ratio=5.6) and a higher degree of oxidation (O/C ratio=0.94). Also, E4/E6 ratio up to 6.8 and salt index of 46.2% for NHSs were at an acceptable level. The decomposition of double bonds of aromatic carbons and the effective transformation of nitrogen into amide and organic nitrogen forms due to ozone oxidation were well proven by elemental analysis of CHNOS and FT-IR spectroscopy. As a result of ozone oxidation, the main pores in Lignite were mainly turned into mesopores. Collectively, the results demonstrated that ozone oxidation, in addition to enhancing the yield and quality of NHSs, provide an end product with a competitive value and a lower price than other commercial nitrogenous humic fertilizers.

Extraction of humic acid (HA) from Lignite coals that are rich in humic compounds has been highlighted in recent years as a superior and prominent research issue. The conventional technique used to extract HA is based on their solubility in alkaline and acidic mediums. Most litertures have reported the extraction time and separation of HA to be 24 hours and the extraction efficiency between 10 to 80%. In this research, the intensification of HA extraction from Lignite coals has been studied. For this purpose, a batch stirred tank reactor (BSTR) was first designed and then fabricated. The processing parameters such as temperature at three levels (50, 70 and 90° C), process time at three levels (1, 2 and 4 hours) and stirring speed at three levels (250, 550 and 850 rpm) were considered as independent variables and extraction yield of HA was considered as dependent variable and the performance of the constructed reactor was compared with a conventional method (Hot Plate device). The statistical results of variance analysis (ANOVA) showed a significant difference between the yield of HA extraction with the reactor and Hot Plate method. Under the same conditions of temperature, stirred speed and process time, the yield of HA extraction with the reactor was 30% higher than the Hot Plate device. The optimal conditions for extraction of HA by the reactor were obtained at temperature of 90° C, stirring speed of 850 rpm and 4 hour process time. In these conditions, 56. 8% of HA was extracted and separated from Lignite coals. The qualitative results of FT-IR spectroscopy showed a predominant aromatic and rich in carboxylic, phenolic and hydroxylic functional groups with aliphatic side chains in the HA structure. The results of quantitative analysis of the CHNOS main elements and atomic ratios (C/N, O/C and H/C), confirms the quality of the used coal and also matches up the quality indices of produced HA with the IHSS standard and commercial Aldrich HA samples.