Search

Non-metallic mineral fillers strongly influence the characteristics and quality of paper. "Visocica" limestone and "Virpazar" dolomite were used to prepare paper samples in this study. The characteristics of such paper samples produced on a laboratory paper machine are presented. The used fillers and paper pulp were also characterized. The following paper characteristics were investigated: gramature, thickness, softness, air permeability, resistance to tearing and stretching, paper ash and retention. The experiments were performed in order to compare the influence of the physico-chemical and structural qualities of the examined carbonate type fillers on the paper properties. The results of the investigation indicated the technological reasons for using these non-metallic mineral raw materials as fillers in the paper industry regarding the mechanical paper characteristics, as well as other properties.

In the paper “Formation mechanism of deep Cambrian dolomite reservoirs in the Tarim basin, northwestern China” ( Zhu et al., 2015 ), we concluded that hydrothermal alteration further enhanced porosity in the deep Cambrian dolomite reservoirs in the Tarim Basin, NW China. Professor Ehrenberg and Bjorlykke made comments that the hydrothermal dolomitization and increase in porosity were not well supported and casted doubt on the exploration potential. We insist the influence of hydrothermal alteration on and large exploration potential in the deep Cambrian dolomite reservoirs due to the unique geological conditions and the recent exploration results.

Summary The paper is divided into two parts. In Part 1, after a brief historical introduction the advantages and disadvantages of using mineral fillers in the manufacture of paper are summarised. Details of the origin, methods of production and basic physical properties of kaolin, natural calcium carbonate, precipitated calcium carbonate, talc and titanium dioxide follow. These are supplemented by more limited information on dolomite, calcium sulphate, calcined clay, satin white, barium sulphate and ultrafine fillers such as hydrated alumina, diatomaceous earth and precipitated sodium aluminium silicate. Factors determining paper permanence are then discussed, and the influence of fillers on permanence considered. Part 2 is concerned with the identification of fillers in paper. It deals with the separation of filler from fibre and methods of elemental analyses. These include wet chemical techniques, details of which are supplied in an appendix, x-ray fluorescence, classical optical spectroscopy and atomic...

Calcium carbonate can replace kaolin as filler and pigment for some kinds of paper. Calcium carbonate can be produced domestically at a lower price than imported kaolin. Domestic materials have to be cleaned by means of flotation to remove silicates and iron-bearing minerals. After flotation, the carbonate concentrate will have to be ground to 50 to 90% - 2 microns for various applications where a specified particle size distribution is required. Different kinds of fine grinding equipment have been tested for this purpose. Mills tested include attrition mills, annular ball mills and vibro-energy mills. It has been found that the attrition mill produces a wide particle size distribution and a product with a large specific surface area. On the other hand, the vibro-energy mill produces a steep particle size distribution and a product with a smaller specific surface area. The paper will also describe classification experiments with small hydrocyclones to produce a steep particle size distribution. The vibro-energy mill has been tested in detail and the influence of various parameters such as frequency, amplitude, solids concentration, media filling and lead angle has been investigated.

Syngas production from biomass gasification is a potentially sustainable and alternative means of conventional fuels. The current challenges for biomass gasification process are biomass storage and tar contamination in syngas. Co-gasification of two biomass and use of mineral catalysts as tar reformer in downdraft gasifier is addressed the issues. The optimized and parametric study of key parameters such as temperature, biomass blending ratio, and catalyst loading were made using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) on tar reduction and syngas. The maximum H2 was produced when Portland cement used as catalyst at optimum conditions, temperature of 900 °C, catalyst-loading of 30%, and biomass blending-ratio of W52:OPF48. Higher CO was yielded from dolomite catalyst and lowest tar content obtained from limestone catalyst. Both RSM and ANN are satisfactory to validate and predict the response for each type of catalytic co-gasification of two biomass for clean syngas production.

The Pila Spi Formation is one of the prominent formations forming continuous ridges in Kurdistan Region. The thickness of the formation ranges from 15 to 110 m, consisting of well-bedded limestone, dolomite, dolomitic limestone, and very rare marl beds. The study area is located about 15 km east of Koya town, next to the abandoned tunnel through a deeply cut valley which has exposed 50 m of the formation. However, the uppermost part of the exposed section may belong to one of the Oligocene formations of Kirkuk Group. The study area was selected within the Pila Spi Formation because the rocks of the same formation and along the same ridge, about 45 km west of the study area showed encouraging results for cement industry. The average CaO is about 51%, whereas the average MgO is 1.8%. Therefore, eight samples were collected at constant thickness from the exposed section. The samples were subjected to X-ray fluorescence (XRF) test to indicate the main oxides in the sampled section. The acquired results from the XRF tests showed that the chemical composition of the exposed rocks within the Pila Spi Formation is suitable for cement industry, also for paper and paint but needs some treatment. Accordingly, another eight samples were collected from the same section to increase the density of sampling, totaling to 16 samples.

In this study, Palm Empty Fruit Bunch (PEFB) was utilized to produce bio-oil through non-catalytic and catalytic pyrolysis process. A fixed-bed reactor was applied to conduct pyrolysis experiments at atmospheric pressure. Comparison of bio-oils obtained from non-catalytic and catalytic pyrolysis wih different pyrolysis temperature was studied in terms product yield. The maximum bio-oil yield of 52.4% was obtained at pyrolysis temperature of 600 °C. Furthermore, based on Gas Chromatography-Mass Spectrophotoscopy (GC-MS) analysis, the percentage of phenolic compounds in bio-oil products from catalyzed pyrolysis showed more higher compared with the non-catalyzed pyrolysis.

Air-gasification has emerged as preferred means of converting biomass to valuable synthesis gas (syngas). In present work, the gasification characteristics of pine sawdust were studied in a small-scale fluidized bed using calcined dolomite as in-bed material. Dolomite is characterized by higher tar conversion and H2 production during biomass gasification. Different operation conditions, equivalence ratios, reaction temperatures and dolomite contents, are studied for their influence on the gas compositions, gas yields, tar yields and higher heating values of producer gas. The results show that increasing either temperature or dolomite content enhances the tar conversion, where the latter accounts for the syngas with the lowest tar content. At 850 °C, the addition of 50 wt% dolomite can increase the gas yield from 1.48 to 1.85 Nm3/kg, and lowering the tar yield from 11.5 to 4.6 g/Nm3. Furthermore, the addition of more dolomite enhances the quality of the product gas, as indicated by increased values of the higher heating values of producer gas. Increasing the dolomite content within the 0–50% range resulted in higher H2 and CO contents, whereas the CH4 content declined. A slight change in CO2 content was observed with increasing dolomite content, which might cause by the limited carbonation. In contrast, the H2 content enhances non-linearly with the increase of dolomite content, which indicates that the catalytic activity of dolomite improves with the increase of dolomite share in the feedstock, due to the reforming of tar over dolomite. Increasing the ER from 0.14 to 0.3 elevates the gas yield, but decreases the tar yield and increases the H2 content in the product gas.

This research studies on the effect of additive (Dolomite) on Biomass powder (Cassava rhizome) which passes Torrefied process and fixed bed at 250 degrees Celsius for one hour and a half. The gasifier with up-draft type was used in this experiment. Air pressure was fixed at 0.1 Bar. The useful heat (Quseful) and Low heating valves (LHV) was investigated by using an Automatic Bomb Calorimeter. Moreover, the dolomite was varied 0, 10 and 15% by weight mixed with Cassava rhizome achieved with Torrefied process. When Low heating valves (LHV) slightly decreases from 21.96±0.22 MJ/kg to 18.15±0.50 MJ/kg, Quseful heat from the burning from gasifier sharply increase when it is mixed with dolomite from 753.34±39.18 to 1,003.97±33.49KJ respectively. The loading of dolomite has significance affecting the useful heat. The present study reveals that low heating valves (LHV) decreases and Quseful heat increase result from dolomite which gives a clean gas product and the Tar molecule can be easily broken. The CO2 gas from the combustion process was absorbed by CaO, which is the main component in dolomite. The cost of mixing 8.9% of Dolomite with Cassava rhizome is the optimum ratio for the biomass combustion process.

This paper presents the results of research on the granulation process of leather industry waste, i.e., tanning shavings. It is economically justified to granulate this waste together with mineral additives that are useful in the processes of their further processing. Unfortunately, the granulation of raw, unsorted shavings does not obtain desired results due to their unusual properties. In this study, the possibilities of agglomeration of this waste were examined by a new method consisting of the production and then the granulation of wet pulp. During granulation, no additional binding liquid is added to the granulated bed. As part of this work, the specific surface of granulated shavings, the granulometric composition of the obtained agglomerates, and their strength parameters were determined. The use of a vibrating disc granulator, the addition of a water glass solution (in the pulp), dolomite, and gypsum made it possible to obtain durable, mechanically stable granules.

Biomass has a great potential for production of syngas and chemicals; however, it has stood in the shadow of natural gas (NG) and coal due to technical problems and issues such as tar formation. In this paper, syngas production from catalytic air–steam gasification of biomass in a fluidized bed was investigated. To enhance the yield of produced syngas and reduce its tar content by cracking, limestone, calcined dolomite, and olivine were used as catalyst. The maximum mole fraction of H2 was found to be 49.1 vol% at 1000 °C and a steam/biomass ratio (S/B) of 1.0 with dolomite present. Compared to olivine and dolomite, calcined dolomite was proved to be more effective for gas production and tar destruction. The results also showed that the particle size has a weak influence on gasifier performance, with only a slight decrease in tar content with decreasing biomass particle size.

Producing biochar from various agricultural and industrial biowastes through pyrolysis is recognized as an eco-friendly approach for solid waste management and remediation of contaminated soils. However, it remains debatable which type of feedstock and pyrolysis temperature could create biochar with better surface functionality and more suitable specific end use. Biochars prepared from rapeseed residue and rice straw at different pyrolysis temperatures (300 and 550 °C) were characterized using various chemical, physical, and spectroscopic techniques. Rapeseed residue and rice straw biochars produced at 550 °C had high pH (9.98 and 10.85, respectively), due to the decrease in total surface acidity with increasing temperature as demonstrated by Boehm titration data, and their high ash contents (18.70% and 24.21%, respectively). The negative charge on high-temperature biochar particles increased with pH, which was confirmed by the reduced zeta potential values (− 42.33 mV for rice straw biochar and − 31.86 mV for rapeseed residue biochar). The mineral phase of both biochars was dominated by sylvite and a small amount of dolomite and calcite, whereas quartz was only found in rice straw biochars. A pyrolysis temperature of 550 °C is suggested for producing biochars that can potentially immobilize toxic elements in the soil.

In the present study, the CaO/Natural Dolomite as a heterogeneous catalyst was applied to synthesize biodiesel from coconut oil. The physico-characteristics of CaO/Natural Dolomite catalyst were determined using X-ray diffraction (XRD), X-Ray Fluorescence, and porosity analysis (specific surface area, average pore size diameter and total pore volume). The performance of CaO/Natural Dolomite catalyst was examined in a batch reactor for transesterification reaction of coconut oil with methanol. From the experiments, the optimum process conditions were achieved at a 60°C of reaction temperature, a 5 wt.% of catalyst amount, and 6 : 1 of methanol to coconut oil mass ratio. The CaO/Natural Dolomite catalyst exhibits high catalytic activity and reliable to be applied in biodiesel synthesis as a heterogeneous base catalyst.

The thermochemical conversion may be an alternative for the final destination of poultry litter wastes. In this study, the effect of calcined eggshell (CE) and calcined dolomite (CD) on slow pyrolysis and air gasification performance of poultry litter waste was evaluated. The catalysts (CE and CD) presented potential for use in the in situ capture of the carbon dioxide produced in the pyrolysis process. In relation to the gasification tests, it can be concluded that both catalysts were effective in cracking the produced tar. Reductions in gas tar concentration of 25.47 and 54.32% were observed for CE and CD, respectively. The catalysts are effective at cracking light hydrocarbons (

We studied the properties of the bio-oil and char from fast pyrolysis of cassava rhizomes in a free-fall reactor, catalyzed by adding various soil conditioners (or improvers) as catalysts to the reactor at 500 °C and 200 g/h feed rate. Four conditioners were evaluated - granular TPI pH11 soil conditioner, volcanic rock, TPI pelletized organic fertilizer and super dolomite - and added at 50% (w/w) of the rhizomes. Bio-oil and gas yields decreased, whereas char yields increased, yielding bio-oil 57–59%, gas 14–20% and char 23–28%. With the catalysts, the bio-oil higher heating value increased, while that of char decreased: for cassava rhizomes with volcanic rock the bio-oil high heating value increased from 19.4 to 23.6 MJ/kg, whereas rhizomes with dolomite led to an increased viscosity from 27 to 34 × 10−3 mm2/s., Fast pyrolysis; Free-fall reactor; Bio-oil; Cassava rhizome; Soil conditioners.

Fluidised bed (FB) technology can be advantageously used for the gasification of solid fuels. Calcined carbonate materials, such as limestone or dolomite, can be used directly in the fluidised bed of the gasification reactor to reform tars in situ and to enhance carbon conversion and cold gas efficiency of the gasification process. However, they exhibit poorer mechanical stability, they tend to be attrited and carried over from the reactor, and their catalytic activity decreases over time. Therefore, a portion of the material has to be replenished continuously or periodically. To decrease the amount of carbonate material that has to be replenished, a lower amount of lime (calcined limestone or dolomite) can be used in the FB, diluted by a mechanically robust material, such as silica sand or olivine. According to the literature, even concentrations in the order of 10–35% wt. of carbonate material in the FB of silica sand have a substantial effect on the decomposition of tars during steam or air gasification. However, the effect of the concentration of lime in the FB has not yet been described for CO2 gasification. In this paper, we focus on the effect of the ratio of calcined dolomitic limestone and silica sand in the FB (0%, 25%, 50% and 100% vol. of dolomitic limestone) for CO2+O2 gasification of biomass and compare it with H2O+O2 gasification at the temperature of 850 °C. The experiments were performed in a semi-autothermal spouting FB reactor, gasifying 1.4 kg h−1 of woody biomass. The effects of the concentration of dolomitic lime in the fluidised bed differed for H2O+O2 and CO2+O2 gasification. When gasifying with H2O+O2, optimal results were found with 50% vol. (35% wt.) lime in the FB, when the yield of tar was similar to the use of pure lime in the FB. When gasifying with CO2+O2, a substantial decrease in tar yield was observed when using 50% vol. (35% wt.) lime in the FB (compared to the use of pure silica sand); nevertheless, the use of undiluted lime in the FB remains the best option to attain minimal tar yield when gasifying with a CO2+O2 gasifying agent. In this case, the tar yield was decreased 8.7-fold, and the tar dew point was decreased by 124 °C (to 71 °C) compared to the non-catalysed case with silica sand being the fluidised bed of the gasifier.

The performances of the primary catalysts olivine, dolomite, γ-alumina and FCC spent catalyst were evaluated in the continuous steam gasification of sawdust in a bench-scale plant equipped with a fountain confined conical spouted bed reactor. The experiments were carried out at 850 °C, and the efficiency of the gasification process was defined by gas yield, H2 production, tar concentration and composition, and carbon conversion efficiency. The benefits of the fountain confiner not only helped to improve the gas-solid contact, and therefore favoured the primary catalysts’ reforming and cracking activity, but also enhanced H2 production and reduce tar formation. Thus, dolomite and γ-alumina recorded the lowest values of tar, 5.0 and 6.7 g Nm−3, respectively, which corresponded to 79% and 72% tar reduction compared to the inert sand, whereas olivine and the FCC spent catalyst recorded higher tar contents, 20.6 and 16.2 g Nm−3, respectively. It is noteworthy that light PAHs were the most abundant species in the tar (60 wt% of the whole tar content).

To investigate the possibilities of utilization of dolomite large size fractions (dropouts) and their effect on plants a five-year experiment was set in 2015. A fertilization value of large fractions (5–7 and 7–10 mm) of dolomite in two doses was studied. The biomass yield of crops in dolomite dropout treatment was around 90% from the treatment using dolomite flour (control). Losses of bases from the soil treated with high doses of dropouts did not exceed the migration losses of the treatment with dolomite flour. Dynamics of dolomite flour dissolution in the soil was empirically modeled. The data prove that high doses of the large-sized dolomite fractions act similarly to standard dolomite flour and have more persistent effects on soil and plants.

The flotation beneficiation of phosphate ore is increasingly facing challenges, especially for finely disseminated sedimentary ores rich in carbonates. This study aims to optimize and assess the impact of key hydrodynamic parameters including pulp density, air flowrate and impeller speed on flotation and metallurgical responses (i.e. grade, recovery, flotation rate constant and selectivity index (SI)). We carried out locked cycle flotation tests using the best conditions from the rougher flotation test to generate an experimental simulation of a continuous circuit. The mineralogical and chemical properties were characterized by mineral liberation analysis (MLA) and inductively coupled plasma optical emission spectroscopy (ICP-OES) techniques, respectively. A modified-McGill bubble size viewer was used for measuring bubble sizes and evaluating the interaction between hydrodynamic factors and bubble diameters. Finally, the design of experiment (DOE) method was applied to determine the relative intensity of the studied factors. It was found that under optimal conditions with the targets of high recovery and maximum SI, the final apatite concentrate achieved a recovery of 86.3% at a grade of 35.5%, while the MgO content was 1.2% and 84.3% of dolomite was removed from a feed ore containing about 25% P2O5, 4.6% MgO, and 41% CaO. Furthermore, another locked cycle flotation test showed that a 0.82% MgO content in the final apatite concentrate can be achieved with an apatite recovery of 75.6% at a P2O5 grade of 36.76% , and a ratio CaO/P2O5 = 1.33. The obtained concentrate in this investigation under the optimum conditions is the highest in both apatite recovery and grade with low MgO content reported in the literature.