Assessment of the Suitability of Coke Material for Proppants in the Hydraulic Fracturing of Coals.

To enhance the extraction of methane gas from coal beds, hydraulic fracturing technology is used. However, stimulation operations in soft rocks, such as coal beds, are associated with technical problems related mainly to the embedment phenomenon. Therefore, the concept of a novel coke-based proppant was introduced. The purpose of the study was to identify the source coke material for further processing to obtain a proppant. Twenty coke materials differing in type, grain size, and production method from five coking plants were tested. The values of the following parameters were determined for the initial coke: micum index 40; micum index 10; coke reactivity index; coke strength after reaction; and ash content. The coke was modified by crushing and mechanical classification, and the 3-1 mm class was obtained. This was enriched in heavy liquid with a density of 1.35 g/cm3. The crush resistance index and Roga index, which were selected as key strength parameters, and the ash content were determined for the lighter fraction. The most promising modified coke materials with the best strength properties were obtained from the coarse-grained (fraction 25-80 mm and greater) blast furnace and foundry coke. They had crush resistance index and Roga index values of at least 44% and at least 96%, respectively, and contained less than 9% ash. After assessing the suitability of coke material for proppants in the hydraulic fracturing of coal, further research will be needed to develop a technology to produce proppants with parameters compliant with the PN-EN ISO 13503-2:2010 standard.

Laboratory Test and Geochemical Modeling of Cement Paste Degradation, in Contact with Ammonium Chloride Solution.

Concrete tanks, in coke wastewater treatment plants, are exposed to aggressive wastewater with high ammonium and chloride content, deteriorating the concrete binder. Due to this, toxic compounds may migrate to the environment. The results of the experimental work presented confirmed the changes in the phase, microstructure and concentration of chlorides caused by the penetration of NH4Cl into the hardened cement paste in dry conditions. Geochemical modeling of the interactions between the aggressive solution, the cement stone matrix and the pore water was performed in order to track the destruction process effects. The results are useful for condition assessment of the structures operating under occasional immersion.

Comparison of the Properties of Natural Sorbents for the Calcium Looping Process.

Capturing CO2 from industrial processes may be one of the main ways to control global temperature increases. One of the proposed methods is the calcium looping technology (CaL). The aim of this research was to assess the sequestration capacity of selected carbonate rocks, serpentinite, and basalt using a TGA-DSC analysis, thus simulating the CaL process. The highest degrees of conversion were obtained for limestones, lower degrees were obtained for magnesite and serpentinite, and the lowest were obtained for basalt. The decrease in the conversion rate, along with the subsequent CaL cycles, was most intense for the sorbents with the highest values. Thermally pretreated limestone samples demonstrated different degrees of conversion, which were the highest for the calcium-carbonate-rich limestones. The cumulative carbonation of the pretreated samples was more than twice as low as that of the raw ones. The thermal pretreatment was effective for the examined rocks.

Impact of Nitrogen Foamed Stimulation Fluids Stabilized by Nanoadditives on Reservoir Rocks of Hydrocarbon Deposits.

The first objective of this experiment was to improve the stabilization of N2 based foam with nanoparticles as an alternative to typical fracturing fluid, which consists of a gelling agent (HPG - hydroxypropyl guar). The second objective of the project was to investigate the damage caused by nanoparticle-based nitrogen foamed fracturing fluids (F.F) on a reference sandstone, using permeability and porosity tests, optical microscope with a Profilometer, and a scanning electron microscope (SEM). The properties of F.F with two types of SiO2 nanoparticles (hydrophilic fumed silica Areosil 300 and silica sol U-2 obtained by the sol-gel method), such as rheology and core damage, were investigated. The discussion of this research results is based on the stability tests carried out with the use of rheology and the foam half-life, formation damage ratio, and observation of exposed samples using SEM and the Profilometer. The permeability and porosity damage ratios of the damaged core samples were found to decrease when nitrogen foamed fluids were used. These results were confirmed with the Profilometer and SEM images. The experimental data showed that the foam stability increased when silica (SiO2) nanoparticles were added. SiO2 nanoparticle-surfactant-stabilized foam for fracturing is superior to traditional water-based fracturing fluids and causes lower core permeability damage than a traditional F.F.

Conversion from cyclosporine to tacrolimus improves renal function and lipid profile after cardiac transplantation.

BACKGROUND: Calcineurin inhibitors (CNIs) have become the cornerstone of immunosuppressive regimens following heart transplantation, but their use is associated with nephrotoxicity. The impact on renal function after conversion from cyclosporine (CsA) to tacrolimus (TAC) is reported. PATIENTS AND METHODS: Fifteen patients (men age 42 +/- 11 years) after cardiac transplantation (HTX) were switched from CsA to TAC (mean time after HTX 21 +/- 6 months). There were 13 male and 2 female patients. Mean cholesterol and LDL level at the time of conversion were 217 +/- 65 ml/dl and and 136 +/- 51 mg/100 ml respectively. Indication for HTX was ischemic cardiomyopathy (CMP) in 8, congenital in 3 and dilatative CMP in the remaining 4 patients. RESULTS: Mean tacrolimus level (microg/dl) at 1, 3, 6 and 12 months were 8.6 +/- 3.3, 8.6 +/- 1.4, 9.2 +/- 2.8 and 9.8 +/- 2.5 respectively. There was a statistically significant improvement in creatinine levels at 1, 3, 6 and 12 months after conversion from baseline 1.9 +/- 0.7 mg/dl to 1.4 +/- 0.5 mg/dl, 1.4 +/- 0.4 mg/dl, 1.3 +/- 0.4 mg/dl and 1.2 +/- 0.4 mg/dl, respectively (p < 0.05). Furthermore, TAC decreased cholesterol as well as LDL-levels during this one-year time frame. CONCLUSION: This study shows that conversion from CsA to tacrolimus after orthotopic heart transplantation improves renal function.

A case of candida albicans mediastinitis after heart transplantation successfully treated with caspofungin.

Reported here is a case of mediastinitis caused by candida albicans and Staphylococcus aureus following a heart transplantation that was successfully treated with caspofungin, antibiotics and mediastinal lavage. A review of the literature revealed that Candida albicans as a cause of mediastinitis has been rarely described. In the few existing reports, evolution was generally fatal, especially in immunocompromised patients, despite treatment with antifungal drugs and antibiotics.