Flotation Efficiency Research Articles

Innovative fluidized bed flotation column for fine particle separation

Flotation columns are extensively utilized to separate fine mineral particles. In highly turbulent environments, the increased collision efficiency between bubbles and particles can lead to improved flotation efficiency of fine particles. The fluidized bed flotation column (FBFC), a new type of flotation equipment, improves the separation efficiency of fine particles by creating a highly turbulent environment in the fluidized zone through the addition of solid particles. This paper investigated the fluidization characteristics, bubble, and gas hold up of the FBFC, along with the flotation efficiency of fine quartz particles. Experimental results showed that introducing gas enhanced the fluidization process in the fluidized bed. The fluidized zone facilitated the fragmentation of bubbles into smaller ones. With increasing liquid velocity, the bubble diameter decreases before subsequently increasing, while the gas holdup initially rises and then declines. The flotation efficiency of fine quartz particles is superior in FBFC with added particles compared to those without added particles. The flotation efficiency of fine particles increases with the rise in both liquid velocity and gas velocity.

Sustainable strategy for high-efficiency flotation of fine low-rank coal: Eco-friendly composite collector prepared from waste oil

This study prepared an innovative composite collector of waste oil (WO) in kitchen waste, suitable for fine low-rank coal (LRC) flotation. It systematically investigated the potential of the composite collector to recover clean coal from fine LRC by froth flotation. The flotation mechanism of fine LRC particles could be elucidated by the combination of FTIR and XPS. The flotation results demonstrated that the WO composite collector significantly increased the yield and combustible recovery of the fine LRC flotation concentrate. Notably, as the dosage of the WO composite collector increased from 200 to 1000 g/t, the clean coal yield rose from 20.08 % to 74.60 %, while the combustible recovery improved from 24.89 % to 91.19 %. FTIR and XPS analyses indicated that the WO composite collector containing C-H/C-C groups adhered to the surface of the coal particles, which enhanced the hydrophobicity of the particles and improved the flotation efficiency.

Effects of sulfation on the flotation capacity of oleic acid in the dolomite and fluorapatite system: A combined experimental and DFT study

Dolomite cannot be efficiently separated from fluorapatite (FA) by oleic acid in an acidic slurry, due to the poor collecting ability of oleic acid. In this work, sulfation was used to improve the flotation performance of oleic acid. Flotation tests showed that the sulfating collector exhibited stronger flotation ability for dolomite. However, the H2SO4-treated FA could not be floated by the sulfating collector. The solubility of the sulfating collector at pH 4.5 was higher than that of HOL at the same pH. Thus, more sulfating molecules and anions were generated in the collector solution, which accounted for the high flotation efficiency of the sulfating reagent. The sulfating collector molecule and anion could adsorb on the H2SO4-treated dolomite surface. Moreover, the reaction of the sulfating collector anions with the dolomite surface generated alkyl Mg/Ca salts.Furthermore, DFT calculations were employed to evaluate the interactions of the sulfating reagent with the H2SO4-treated dolomite surface. The sulfation produced two isomers. The most stable isomer, i.e., 10-sulfooxy stearic acid (SOA), was used in the calculations. The SOA anion could vertically or paralelly adsorb onto the dolomite. The parallel structure was more stable, where the COO− and OSO3− groups of SOA anion bonded with two metal atoms on the dolomite surface. These findings suggest that the sulfation collector is suitable for the reverse flotation of collophane.

Simulation study on flow field regulation of flotation column with stirring device

ABSTRACT Flow field regulation plays an important role in the optimization of column flotation units with agitation function. This paper aims to discuss the regulating effect of baffle design on the flow field in stirred column flotation units by numerical simulation. A series of geometric models of changing baffle structure and layout were established, and detailed flow field simulation analysis was carried out by using COMSOL software. The results show that the internal flow field of the traditional standard cylindrical tank will cause the solid particles to adhere to the wall movement and the bubbles to the middle area, resulting in the uneven distribution of particles and bubbles, and the internal flow field is not conducive to the mineralization process and the stability of the foam layer. This limitation can be significantly improved by introducing baffles. The results show different baffle shapes and layouts are as follows: wide and narrow on top, narrow on the bottom and wide on top, and only arranged at the bottom of the column body, can increase the average turbulent kinetic energy in the collision zone by 22%, 46% and 43%, and the average turbulent dissipation rate by 18%, 43% and 36%, respectively, while maintaining the turbulence intensity in the transport zone. Among them, the baffle plate with wide top and narrow bottom has the best effect. Arranging baffles with a length shorter than 2/3 of the height of the cylinder at the upper part inside the cylinder can also enhance the turbulence intensity in the collision zone, but at the same time, it also increases the turbulence intensity in the transport zone. Moreover, as the length of the baffle decreases, the enhancement effect becomes stronger. Since this method significantly affects the transport zone, it is more suitable for columnar mixing devices. The study also reveals that by adjusting the proportion of wide and narrow baffles, the center of the turbulent region can be laterally shifted to the short baffles, and the flow field distribution can be adjusted. Meanwhile, with the increase in the number of long baffles, the intensity of the flow field in the device will gradually decrease. By moving the center of the turbulent region to the side inlet, the particle dispersion can be accelerated, but in general, the particles will accumulate toward the region with lower turbulence intensity. These findings have important guiding significance for the design and optimization of the flow field of the stirred column flotation unit, which is helpful in improving the agitation uniformity and flotation efficiency.

Enhancing lepidolite flotation efficiency with the novel LCJ collector: comparative analysis and mechanistic insights in Jiangxi Province’s lepidolite resources

ABSTRACT This study evaluates the flotation performance of a novel combination collector, LCJ, on lepidolite from Jiangxi Province, China. A comparative analysis with the on-site collector EO demonstrates an economically efficient separation scheme for lepidolite. Results show that LCJ outperforms EO in capturing lepidolite. Employing 400 g/t sodium hexametaphosphate as an inhibitor and 290 g/t LCJ as a collector, a flotation process with one rougher, two cleaner, and two scavenger stages achieves a lepidolite concentrate with a Li2O grade of 2.10% and a recovery of 78.62%. LCJ also enhances foamability within conventional air-inflation ranges. Infrared testing, Zeta potential analysis, and contact angle measurements indicate similar organic adsorption on the lepidolite surface for both collectors. However, LCJ significantly influences the Zeta potential, increasing hydrophobicity. These findings confirm LCJ as an efficient and selective collector for lepidolite flotation, with promising application prospects.

Enhancing flotation efficiency: Optimizing galena and chalcopyrite separation through high-temperature pre-oxidation with recycled sulfuric acid

Galena and chalcopyrite pose challenges in their separation owing to their similar surface chemistry. The flotation separation of galena and chalcopyrite significantly depends on the use of depressants. However, conventional depressants are often associated with several drawbacks, such as toxicity and inefficiency. Hence, exploring efficient and environmentally friendly techniques to separate galena and chalcopyrite is vital. This study investigated the use of sulfuric acid as a surface oxidant for the pre-oxidation treatment of galena and chalcopyrite at high temperatures. This approach facilitated acid recycling and eliminated the need for multiple flotation chemicals. The floatability of galena and chalcopyrite was investigated through micro-flotation. The results revealed that at a pre-oxidation temperature of 100℃, galena exhibited a recovery rate of only 9.98 %, while chalcopyrite maintained a recovery rate of 96 % across the temperature range. The selective depressant mechanism of sulfuric acid in the flotation separation of galena and chalcopyrite was investigated through scanning electron microscopy, zeta potential measurements, X-ray photoelectron spectroscopy, thermodynamic calculations, and electrochemical analyses. The results indicated that the high temperature facilitated the dissolution of the sulfide layer on the galena surface. Consequently, S2− ions underwent oxidization into SO42− to form a stable oxide film on the galena surface through interaction with Pb2+. Conversely, the high-temperature pre-oxidation had a minimal effect on the surface of chalcopyrite, indicating selective oxidation benefits. Findings from the pre-oxidation floatation separation test of galena–chalcopyrite mixtures revealed the efficient and thorough separation of the two minerals under high-temperature pre-oxidation conditions. The lead concentrate obtained from the floatation process exhibited a Pb grade of 79.38 % and a recovery rate of 97.17 %, while the Cu concentrate featured a Cu grade of 32.14 % and a recovery rate of 97.06 %. Additionally, the sulfuric acid solution was recycled. Overall, this study provides a sustainable and cost-effective approach for the green separation of copper–lead sulfide ores.

Effect of the Tundish Inhibitor Design on the Flotation Efficiency of Nonmetallic Inclusions: Water Modeling and Mathematical Simulations by the Reynolds Stress Model

Effect of the Tundish Inhibitor Design on the Flotation Efficiency of Nonmetallic Inclusions: Water Modeling and Mathematical Simulations by the Reynolds Stress Model

Effect of Pre-Sulfidization on the Octadecyl Amine Adsorption on the Smithsonite Surface and Its Flotation.

The low-grade zinc oxide ore was sulfidized to increase the efficiency of flotation, but the effect of pre-sulfidization on the adsorption mechanism of octadecyl amine (ODA) on the smithsonite surface is currently unclear. In this study, the effect of pre-sulfidization on the adsorption mechanism of ODA and the flotation behavior was studied using smithsonite and pre-sulfidized smithsonite as the samples by zeta potential, contact angle measurement, total organic carbon analyzer (TOC), quartz microcrystalline balance (QCM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and micro-flotation tests. Micro-flotation tests showed that the pretreatment of sulfidization could improve the floatability of smithsonite. Zeta potential and contact angle measurements demonstrated that pre-sulfidization could favor the adsorption of ODA, which is further confirmed by the adsorption tests of ODA using TOC and QCM. Furthermore, FTIR and XPS analysis showed that pre-sulfidization changes the adsorption mode of ODA, changing it from physical adsorption to chemical adsorption. These results suggested that the favorable effect of pre-sulfidization on the adsorption of ODA and the flotation of smithsonite might provide important guidance for industrial application.

Improve flotation efficiency of refractory tungsten ore and reduce carbon emission in flotation process: A case study of Sandaozhuang deposit in Henan, China

With the rapid consumption of tungsten ore resources which were easy to beneficiation, the low-grade refractory scheelite has become the main source of tungsten production. In this study, a new reagent recipe was proposed to improve scheelite flotation efficiency and reduce carbon emission in flotation process by taking Sandaozhuang strongly altered ore as an example. The mineralogical study indicated that the content of WO3 in this ore was 0.0952 %, and 83.16 % of WO3 occurred in scheelite. The high content of calcium-containing gangue, easy-argillation gangue and fine scheelite jointly made it difficult to recover scheelite efficiently. The batch flotation tests shown that under the conditions of Na2CO3 1800 g/t, SS 600 g/t, SG 60 g/t, engine oil 20 g/t and FX-8 180 g/t, a rough concentrate with WO3 grade of 1.503 % and WO3 recovery of 79.40 % can be obtained. The industrial tests and application shown that this new reagent recipe had good industrial applicability and stability, and was conductive to improve the efficiency of the whole flotation process. The economic and environmental benefits analysis found that the application of this new reagent recipe in a 10,000 t/d scheelite flotation plant can create annual additional economic value of more than CNY 20 million, and reduce annual carbon emissions by more than 5000 t. Therefore, this new reagent recipe was worth popularizing and applying in similar refractory scheelite flotation plants.

Improving Efficiency of Flotation for Tavantolgoi Coal after Interplay Combination Ultrasonic and Electrolysis

Improving Efficiency of Flotation for Tavantolgoi Coal after Interplay Combination Ultrasonic and Electrolysis

Flotation of ultra-low ash coal combined with ultrasonic pretreatment

ABSTRACT Ultra-low ash coal is an essential clean energy and material. The preparation of ultra-low ash coal by flotation is facing challenges due to the inherent drawbacks. This work aims to enhance the flotation efficiency of ultra-low ash coal by ultrasonic pretreatment. Timed-release flotation experiments were conducted with ultrasonic pretreatment before and after collector addition. The results showed that the recovery and combustible recovery and flotation perfect index of clean coal increased after ultrasonic pretreatment. Additionally, the flotation circuits can reduce from three to two times to obtain clean coal with ash content around 5%. The particle size distribution of coal varied from unimodal to bimodal after ultrasonic pretreatment no matter whether collector was added, indicating that ultrasonic had both dispersing and flocculation effects. Scanning electron microscope (SEM) analysis illustrated that the surface of coal was cleaned due to the ultra-fine gangue particles coated on coal surface was dispersed, and the flocculation of low-ash coal particles was promoted after ultrasonic pretreatment. Consequently, the ultra-low ash coal with higher recovery and quality could be obtained with simplified circuits.

Investigation of Flotation Bubbles Movement Behavior under the Influence of an Immersed Ultrasonic Vibration Plate

Ultrasonic flotation is widely used as an efficient mineral separation method. Its efficiency is related to the adhesion behavior between fine particles and flotation bubbles, which can be influenced by the bubbles’ movement behavior. This paper used two immersed ultrasonic vibration plates to generate ultrasonic action and investigated the effect of ultrasonic action on the rising process of flotation bubbles. The distribution, aggregation and fusion, velocity, and other characteristics of bubbles generated by different needle apertures were studied by experimental and simulation methods. The results showed that a 0.4 mm needle produced bubbles that were more evenly spaced and more uniform in size and shape. The ultrasonic action can make the bubbles aggregate together and reduce the bubble rise velocity, as well as prolong their time in the flotation process at the same time. It is beneficial to the sufficient collision and adhesion behavior between flotation bubbles and particles, eventually improving the efficiency of mineral flotation.

Impact of power input in pulp conditioning on coal flotation and real-time characterization by focused beam reflectance measurement (FBRM)

ABSTRACT Pulp conditioning is a necessary procedure in the coal flotation industry, and optimizing the power input of such processes is in favor of improving flotation efficiency and reducing costs. This paper applied a pulp conditioning system combined with the focused beam reflectance measurement (FBRM) to investigate the impact of power input on coal flotation. Under the same energy input, the highest flotation efficiency of 50.09% was achieved in a pulp conditioning pattern of 1800 rpm-3 min, but the flotation efficiency reached only 36.13% in 1200 rpm-7.2 min. The kerosene collector can disperse into large numbers of droplets that exceed 2000 counts/s at size fractions of −10 μm and 20–50 μm in high power input and achieve better adsorption on coal. In the pulp conditioning process, the coal particle numbers of −50 μm size fraction decreased significantly from 15,000 counts/s to nearly 8000 counts/s at 32.3 W power input and coarse aggregates of 50–1000 μm size were detected. Under high power input conditions caused by high agitation speed, extra energy contributed validly to the kinetic energy of coal particles/collector droplets and the generation of oil-water and oil–coal interfaces. The shear flocculation behavior induced by the high power inputs in pulp conditioning is favorable for the flotation recovery of fine and ultra-fine particles.

Influence of Carbonated Pyrolysis Oil Recycled from Scrap Tires on Metallurgical Efficiency of Coal Flotation

This research assesses the effect of carbonated pyrolysis oil (CPO) derived from scrap car tires on the metallurgical efficiency of coal flotation as a flotation additive. Using a statistical experimental design, the influence of various operational variables, including solid percent of feed pulp and dosages of reagents, i.e., CPO as an additive, diesel oil as a collector, and pine oil as a frother, on the ash content and yield of the final concentrate were investigated. Experimental data vary significantly based on operational conditions, ranging from 6.6% ash content with a 15% yield to 19.1% ash content with a 76.8% yield. The composition of the pyrolysis oil was identified by using Fourier transform infrared spectroscopy (FTIR). The analysis of variance (ANOVA) of experimental results demonstrated that almost all variables had a substantial effect on the flotation responses, positive or negative, depending on the variable or variable interaction. It was discovered that the usage of CPO intensified the total yield and ash content of concentrate in a nonlinear fashion in a range of 15% and 4%, respectively. The results revealed a non-selective interaction effect between CPO and pine oil, as well as competitive adsorption between diesel oil and CPO, which contributed to the curved behavior of flotation measurements. The detrimental effect of CPO on the flotation response of the studied coal sample was also related to the interaction of the hydrophilic groups in the CPO structure and the oxide groups of ash material in coal particles. This work shows the potential of carbonated pyrolysis oil to enhance coal flotation performance and sheds light on the underlying mechanisms.

Linking ores flotation results to the Kinsenda copper deposit mineralogical features: enhancing the recovery of copper retained in flotation tailings

ABSTRACT Since the Kinsenda concentrator commissioning in 2015, the selective flotation of mixed copper ores (67% as sulphides and 39% as oxides) from the Kinsenda deposit (DR Congo results in a recovery yield of 57% of copper as oxides versus 98% as sulphides.. Talings from the flotation of sulphide minerals contain 1.14% as total Cu including 0.38% as oxides. This research adopted a geometallurgical approach for enhancing the recovery of not floated copper. Consequently, it thoroughly studied the Kinsenda copper deposit mineralogy to explain causes of poor results of the industrial flotation of copper and conducted chemical and granulochemical analyses of tailings to describe and comprehend the copper behaviour during flotation. The effects from particles size in tailings, and the reagents’ suite components and their dosages on the copper flotation efficiency were investigated. Flotation results were significantly improved when tailings contain 70% particles with size smaller than 106 μm were floated using a reagents suite including 3600 g per t NaHS (sulphidiser), 360 g per t SNPX (collector) and 360 g per t AM810 (promoter). Indeed, the concentrate's grade in total copper reached 23.75%, with a recovery yield of 91.07% and 15.41% in oxidised copper, with a recovery yield of 91.26%.

Evaluation of industrial performance of a new three phase fluidized bed flotation column-Based on product size characterization

There are still a large number of minerals processed by flotation every year, so it is extremely important to improve the flotation efficiency in industrial production. This study established an experimental test platform for new three-phase fluidized bed flotation column (TFC). The effects of different operating conditions and equipment parameters (apparent gas velocity, apparent liquid velocity, and filling height) on separation effect of coal slime were investigated. Relationship between turbulence intensity inside TFC and the flotation effect of coal slime with different particle sizes was analyzed. Results show that turbulence intensity in fluidized environment can be influenced by adjusting operating conditions to increase the probability of adhesion and collision of fine-grained particles with air bubbles. Differences of particle size distribution in the radial and axial directions of TFC are influenced by settling velocity. Increasing circulation volume can increase residence time of particles in flotation process. Micro and nano bubbles have excellent characteristics which are beneficial to particle collision and adhesion. By adjusting the parameters, it can meet needs of mineral separation and mineralization environment and realize effective recovery of slime with different particle sizes. This study was conducted by analyzing the flotation of fine particles by TFC during industrial platform testing. By evaluating the industrial performance of TFC, it provides a reference for future industrial large-scale applications.

The development of an efficient precipitation-flotation-dewatering (PFD) process for acid mine drainage treatment

Acid mine drainage (AMD) stands as a prevalent environmental challenge across numerous mining sites, often addressed through the high-density sludge (HDS) process, a typical neutralization and sedimentation process. However, despite its widespread use, the HDS process requires prolonged treatment durations and presents challenges in sludge dewatering and site relocation, thus falling short of an optimal solution. In this study, an efficient precipitation-flotation-dewatering (PFD) process was developed and optimized as a viable alternative to the HDS process, offering efficient AMD treatment. The experimental results indicate that over 90 % of ions were successfully precipitated by employing CaO as a neutralizing agent to adjust AMD pH to 10.0. Flotation was then conducted with a low-profile flotation column after adding an optimal concentration of 10 mg/L of A-100 flocculant and 400 mg/L of NaOL. Compared with original AMD, the final removal of toxic and hazardous ions of Fe, Al, Cd, Sn, Co, Ni, Zn, and Mn were 97.61 %, 98.85 %, 98.21 %, 97.78 %, 97.22 %, 99.34 %, 99.89 %, and 99.14 %, respectively. Additionally, the solid content of produced sludge was 27 %. Mechanistic inquiries revealed that A-100 and NaOL both chemically adsorbed on the particle surface and respectively enhanced the collision and attachment probabilities between precipitate particles and bubbles, thereby augmenting the separation efficiency. Furthermore, shortening the flotation column reduced the particle flotation path, thereby improving the flotation efficiency. The efficient PFD process exhibits significant advantages of rapid and effective AMD treatment, high sludge solid content, small footprint, and high relocatable convenience, demonstrating satisfactory cost effectiveness and significant potential as a replacement of the HDS process for AMD treatment.

Auxiliary collector optimizing foam characteristic and adsorption behavior towards efficient flotation desilication of bauxite

The desiliconization of bauxite through flotation poses challenges due to the limitations of conventional collectors like oleic acid. Hence, there is an urgent need to explore more selective alternatives to enhance efficiency. In this study, sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SLS), and benzohydroxamic acid (BHA) are explored as auxiliary collectors with sodium oleate (NaOL) to enhance its efficiency and selectivity. Bench-scale tests reveal that combined collectors exhibit superior flotation efficiency and concentrate quality compared to NaOL alone, both in laboratory settings and actual bauxite ores. Detailed mechanistic insights are provided from both macroscopic and microscopic perspectives. Macroscopic analyses uncover differences in foam and pulp properties among the combined collectors, indicating that the NaOL + BHA system offers moderate foaming performance, stability, and homogeneity, enhancing collection efficacy and selectivity. Microscopic investigations elucidate the adsorption mechanism between combined anionic collectors and mineral surfaces using the quartz crystal microbalance with dissipation (QCM-D) and Fourier transform infrared spectroscopy (FTIR). QCM-D analysis shows that SDS, SLS, and BHA weaken NaOL adsorption on kaolinite surfaces and accelerate reagent desorption, with BHA having the most significant effect. These findings provide valuable insights for optimizing bauxite flotation processes with improved efficiency and selectivity.

Characterization and Beneficiation of Fanibi Laterite for Nickel Metal Recovery Using Froth Flotation Method

This study investigates the characterization of Fanibi Laterite and the efficiency of froth flotation to beneficiate nickel from its host rock sourced in Akure, Ondo State, Nigeria. A sample of the laterite was obtained and characterized by the use of an X-ray fluorescence Spectrometer (XRFS), X-ray diffractometer (XRD), and Scanning electron microscope with Energy dispersive spectroscope (SEM/EDS). The ore was comminuted to its liberation size of -125 + 90 µm. The froth flotation process was done using Sodium hydroxide and Hydrogen tetraoxosulphate (VI) acid as hydrogen potential (pH) modifier within the range of 4,5,7,9 and 10. However, other reagents are sodium oleate as the collector, potassium dichromate as the depressant, and oleic acid as the frother. The froth and depressed obtained were dewatered and characterized using XRFS. The result revealed that the ore contained 35.65% Si, 8.24% Al, 10.87% Fe, and 0.07% Nickel. It also included some other associated minerals such as Zn, Mg, Ti, Co, and Mo in trace form of less than 1 %. XRD analysis reveals nickel as nickel iodate. The result reveals nickel assays of 0.14, 0.20, 0.15, 0.25, and 0.12%, while their recoveries are 70.82, 67.80, 86.70, 98.04, and 86.98%, respectively. The optimum nickel recovery of 98.04% was attained at a pH of nine (9). It was concluded that froth flotation could successfully beneficiate Fanibi laterite ore for nickel. At the same time, other minerals such as Titanium, Molybdenum, Tin, and Tungsten were present to be extracted for Metallurgical applications.

Effects of micro- and nano-bubbles on the flotation separation of unburned carbon from coal fly ash

ABSTRACT Nanobubble technology has found extensive use in enhancing the flotation efficiency of various minerals. The utilization of nanobubbles in flotation encompasses bulk nanobubbles, surface nanobubbles, and microbubbles; however, a comprehensive comparison of their respective roles is lacking. Furthermore, there is a dearth of studies on employing nanobubble systems in the flotation of coal fly ash. The coal fly ash characters were initially studied to reveal its ultrafine size (d50: 24.80 μm) and porous structure that includes a multitude of hydrophilic functional groups. These attributes contribute to the inadequate hydrophobicity of unburned carbon within the ash. Subsequently, the effects of different collector types, frother types, and air flow rates on the efficiency of carbon removal using conventional flotation methods were examined. Comparative analysis showed that conventional flotation using diesel oil outperformed that which employed kerosene as the collector. Additionally, higher carbon removal efficiency was achieved using MIBC, with a longer carbon chain length, as the frother, as opposed to sec-Octyl alcohol. Furthermore, a direct relationship between air flow rate and coal fly ash flotation performance was observed – higher air flow rates corresponded to improved flotation outcomes. Finally, a comparison between conventional flotation and nanobubble-assisted flotation (utilizing bulk nanobubbles, surface nanobubbles, and micro-nanobubbles) was conducted. Remarkably, micro-nanobubble flotation yielded the most promising results, with the lowest loss-on-ignition in flotation tailings (3.15%) and the highest removal efficiency of unburned carbon (85.01%). These findings satisfied the loss-on-ignition requirements of Grade I fly ash standards.