Pelleting Process Research Articles

BioWorma as an Aid for Controlling Ruminant Nematode Parasites

Abstract Nematode-trapping fungi are biological control agents used against the larval stages of gastrointestinal nematodes in livestock feces. These fungi are normal soil inhabitants where they feed on a variety of non-parasitic soil nematodes. Of the various fungi tested, Duddingtonia flagrans spores (BioWorma, International Animal Health Products, Australia) have been shown to survive passage through the gastrointestinal tract of ruminants. After defecation, the spores germinate and grow in the feces to form sticky, sophisticated traps/loops which are able to trap the developing larval stages in the fecal environment. This form of control has been successfully applied under field conditions and is an environmentally safe biological approach for forage-based feeding systems. BioWorma has recently been approved for use in the United States. The primary delivery system is mixing BioWorma into supplement feedstuffs daily where each animal has the opportunity to consume an adequate amount of the mixture. To achieve optimum control of larvae during the transmission season (May–October), BioWorma needs to be fed for a period of no shorter than 60 days, starting at the beginning of the grazing season (especially young after weaning). Feeding BioWorma to dams during late pregnancy and lactation will also help to reduce pasture contamination, especially for growing young that will graze the same pasture. Another delivery system is mixing BioWorma into loose mineral supplement where animals will consume it free choice. The mineral needs to be kept covered and dry. The spores cannot be incorporated into pellets as the heat of the pelleting process will kill the spores. One drawback in using BioWorma is the relatively high cost. Research is being conducted to evaluate other delivery schemes that could be more cost effective. This product is the only control method that targets nematodes on pasture, where a majority of the total population reside.

Selecting a Biomass Pelleting Processing Depot Using a Data Driven Decision-Making Approach

Bioenergy is one of the potential solutions to satisfy the extensive demand for energy and reduce fossil fuel dependency. For biomass to be an efficient source of bioenergy, it must be converted to a usable form, one of which is pellets. This study compares three commonly used methods to produce pellets in a biomass depot and presents a framework to select the most effective and economic pelleting processes. The comparison is performed using a data driven decision-making method called the Preference Index Selection Method (PSI). We considered three main pelletization technologies and compared four of their most critical attributes. The three popular biomass pellet processing methods used for this study are the conventional pelleting process (CPP), the high moisture pelleting process (HMPP), and the ammonia fiber expansion (AFEX). These processes were evaluated from both economic and environmental perspectives. We used the state of Mississippi as a testing ground for our analyses. The results obtained through the PSI method were validated with the Grey relational analysis (GRA) method. The results revealed that of the three available pelleting processes, the conventional pelleting process and the high moisture pelleting process were the most economic and environmentally friendly.

Ultramicroporous carbon granules with narrow pore size distribution for efficient CH4 separation from coal‐bed gases

AbstractThe adsorptive separation of CH4 from low‐grade coal‐bed gas can be performed at decentralized and remote coal mines, and it uses more energy‐ and is cost‐efficient than the traditional cryogenic distillation process. Herein, we present a facile method to prepare ultramicroporous carbon granules with a narrow pore‐size distribution at 0.5–0.6 nm. To our knowledge, such centered and uniform pore‐size distribution in carbon granules has never been reported. The carbon granules can be directly utilized in adsorption columns without a granulation or pelletization process. The granular oil‐tea‐shell‐derived porous carbon (GOC‐2) exhibited a record‐high CH4 uptake of 1.82 mmol/g and CH4/N2 selectivity of 5.8 at 1.0 bar and 298 K among carbon granules. The excellent CH4/N2 separation performances were confirmed from the results of dynamic breakthrough experiments and pressure swing adsorption simulations. This work provides a novel strategy for developing ultramicroporous carbon granules and guides the future design of efficient CH4/N2 separation adsorbents.

PREDICTION FOR TOTAL MOISTURE CONTENT IN WOOD PELLETS BY NEAR INFRARED SPECTROSCOPY (NIRS)

Mankind consumes as many fossil fuels per year as nature produced during a million years. Furthermore, energy consumption has tripled in the last 60 years, and is expected to be doubled in 2050, due to the technological and economic takeoff of large emerging powers. In light of this scenario, a change in energy policies should be aimed to promote energy efficiency and the use of sustainable energy resources, such as bioenergy, safely and environmental friendly. Biomass fuels take a main role in the EU's energy and climate policies, aimed at reducing CO2 emissions and combating Climate Change. Quality control of biofuels and knowledge of their characteristics reach a large relevance in any industrial application based on the energy use of biofuels. NIRS technology (near infrared spectroscopy, Near Infrared Reflectance Spectroscopy) is based on the interaction between electromagnetic radiation and material, and now is presented as an encouraging technological tool for quality testing of solid biofuels, since it is a non-destructive and much faster and cheaper analytical technique than traditional ones, which are based on current ISO standards. That interaction appears as spectral vibrations (energy absorption or absorbance) that are properly processed, allowing to measure the most important physical-chemical properties of solid biofuels in a fast, simple and non-destructive way. Wood pellet is the highest quality solid biofuel in the current biomass market, which is regulated by ENplus® certification scheme in the European-wide, ensuring the quality of product to consumers. Low heating value is the most important parameter of solid biofuel, and is strongly linked to total moisture content, so the control of moisture is key factor during pelletizing process. The original research carried out in this work allows to present the development of a NIRS prediction model for total moisture in wood pellets, in the range of values of 5 – 10 %, providing a much faster and more automated methodology for product quality control, both in production plants of wood pellets and in power plants with wood pellets as fuel. Keywords: near infrared spectroscopy, wood pellets, quality control, moisture, prediction model

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF INNER FLOW FIELD OF SEED PELLETING PREMIXER IN SPOUTED FLUIDIZED BED

In order to explore the temporal and spatial distribution and motion state of the grains of wheatgrass (Agropyron) seeds and powder in pelleting process, and to find the optimal inlet air speed of pelleting premixer, the pelleting forming mechanism was revealed. Based on Herz-Mindlin contact theory, the contact mechanics model of seed and powder was established. Besides, CPFD software was used to model and simulate the pelleting premixer, and the contact, collision and friction rules among particles were analysed. The simulation and experimental results show that with the increase of inlet wind speed, the bed expansion increases and the unit volume particle concentration decreases, while the air pressure difference only slightly increases. When the inlet wind speed is set at 3.5 m/s, the atomizing nozzle velocity is set at 4.1 m/s, and the seed coating agent flow rate is 0.36 L/min, the particles are suspended due to air isolation, forming a spouted fluidized bed. It is good for seed and powder contact and rapid prototyping. In this time, the pelleting qualified rate was 95.8%. The results provide theoretical basis and technical support for the research of small irregular seeds pelletizing technology.

The effect of hydrothermal processing on the performance of broiler chicks fed corn or sorghum-based diets

This study aimed to evaluate the effect of hydrothermal processing method on growth performance, digestive organ morphometry, activity of pancreatic amylase and lipase, plasma glucose and insulin concentration of broiler chicks fed post-hatching diets containing different carbohydrate sources (corn or sorghum). The experiment was carried out in a completely randomised design following a 2 × 2 factorial arrangement (factor 1: pelleting or extrusion processing; factor 2: corn or sorghum) with six replicates of 30 chicks each. Chicks were fed the diets in transport boxes for 24 h after hatch (post-hatch phase). After the post-hatch phase, all the chicks were housed and fed the same pre-starter diet. The response parameters were evaluated after 24 h and at seven days of age. The data were subjected to two-way ANOVA and the means compared by the Tukey post-hoc test (5%). After 24 h, chicks fed pelleted post-hatch diets showed a lower weight loss. Chicks fed diets containing sorghum had improved absorption of nutrients from yolk sac denoted by the reduced yolk sac weight. Broiler chicks fed extruded corn-based diets showed higher specific amylase activity (P < 0.001) and lower glucose concentration at 24 h after hatching (P < 0.001) while at seven days of age they showed the worst feed conversion rate (FCR) (P = 0.002). No difference on FCR was observed among the other groups (P> 0.05). Hydrothermal processing method nor carbohydrate source affected digestive organ weight of broiler chicks (P > 0.05). Broiler chicks fed extruded sorghum-based diets showed increased blood glucose levels in the post-hatch phase while the animals fed pelleted corn-based diets showed improved FCR during pre-initial phase.

Life Cycle Perspectives of Using Non-Pelleted vs. Pelleted Corn Stover in a Cellulosic Biorefinery

Cellulosic biorefineries have attracted interest due to the growing energy security and environmental concerns related to fossil fuel-based energy and chemicals. Using pelleted biomass as a biorefinery feedstock can reduce their processing inputs while improving biomass handling and transportation. However, it is still questionable whether energy and emission savings from feedstock transportation and processing can justify pelletization. A life cycle assessment approach was used to compare energy consumption and greenhouse gas (GHG) emissions from pelleted and non-pelleted corn stover as a biorefinery feedstock. Operations considered were pelleting, transportation, and soaking in aqueous ammonia (SAA) pretreatment. Despite greater GHG emissions (up to 25 times higher than the transportation) generated from the pelleting process, the model showed a significant opportunity to offset and even reduce overall GHG emissions considering the pretreatment process benefits. Our process energy analysis showed that SAA pretreatment of pelleted biomass required significantly lower energy inputs (56%) due to the lower-severity pretreatment’s effectiveness. Higher pretreatment solid loadings are allowed when pelleted biomass is used and this reduces the process chemicals and water requirements by 56% and 49%, respectively. This study demonstrated that the SAA pretreatment of pelleted biomass might be a feasible option as the cellulosic biorefinery feedstock.

Online size distribution measurement of dense iron green pellets using an efficient and multiscale nested U-net method

Accurately measuring the pellet size distribution during the pelletizing process is critical, because the pellet size distribution is a key quality indicator and affects the efficiency of the blast furnace. In this study, a method based on a convolutional neural network is proposed to measure the pellet size distribution in the stable area of a rotary disc. The proposed network only uses simple convolution layers in sequence to realize multiscale performance; furthermore, it uses a bottleneck layer and a concatenate path to improve the computing efficiency and alleviate the vanishing gradient problem, respectively. Various experimental results demonstrate that the proposed network outperforms other comparison methods in segmenting overlapped pellets, especially pellets of different sizes. The pellet size distribution obtained by the proposed method agreed well with the manual sieving results. Moreover, the computing time of the proposed method can meet the requirements of online size distribution measurement.

Pellet Quality of Corn-Based DDGS

The rapid growth of corn-based dry grind ethanol plants over the past decade in the US has resulted in a great increase in production of the coproduct DDGS (distillers dried grains with solubles). Since some physical properties like low bulk density and poor flowability can impact the market potential of DDGS, pelleting of DDGS can be one of the easiest ways to improve this situation. Pellet quality is the focus of this project. The pelleting process was conducted with three initial DDGS moisture contents and two different dies; a total of six runs were completed to produce DDGS pellets. The physical qualities of pelleted DDGS were determined by measuring durability, bulk density, angle of repose, and color of the pellets. The results showed that the durability ranged from 42% to 89%, the highest pellet durability occurred when the moisture content was 20% db and the die diameter was 1/8 in. The bulk density increased when the DDGS moisture content decreased, and the highest bulk density was observed when the moisture content was 10% db and the die diameter was 1/8 in.

Hydrochar pellet produced from hydrothermal carbonization of fecal sludge

Hydrochar, a solid product of hydrothermal carbonization of biomass, has been used in many applications, especially on sustainable bio-energy. In this research, the hydrochar produced from fecal sludge was transferred into pellets using a hydraulic press at various mixing ratios of hydrochar, binders (lignin, starch, and calcium hydroxide), and water. The produced hydrochar pellet characteristics such as energy content, pellet density, and compressive strength were determined. The pelletizing process resulted in increased density and compressive strength of the hydrochar pellets, but the energy content was relatively stable. Adding water resulted in decreased density and compressive strength of the hydrochar pellets. The optimum mixing ratio of hydrochar/starch/water for the pelletizing process was suggested to be 85:15:0 by weight. At this optimum condition, energy contents, densities, and compressive strengths of the hydrochar pellets of 20.1–20.5 MJ/kg, 995–1020 kg/m3, and 8.5–9.2 kN/m2, respectively, could be achieved. At complete combustion, particulate matter sizes of 0.4–2.1 μm in diameters were the main PM component, and the emissions of carbon dioxide and sulfur dioxide were estimated to be 176 g and 2 g per 100 g of the hydrochar pellet, respectively.

The single-particle model of calcium carbide production and strengthening mechanism of the novel pelletizing process

The single-particle model of calcium carbide production and strengthening mechanism of the novel pelletizing process

Design modification of iron ore bearing transfer chute using discrete element method

Purpose The dryer feed chute of the pellet plant plays an important role in the pelletizing process. The chute discharges sticky and moist iron ore fines (&lt;1 mm) to the inline rotary dryer for further processing. Since the inception of the installation of the dryer feed chute, the poor flowability of the feed materials has caused severe problems such as blockages and excessive wear of chute liners. This leads to high maintenance costs and reduced lifetime of the liner materials. Constant housekeeping is needed for maintaining the chute and reliable operation. The purpose of this study is to redesign the dryer feed chute to overcome the above challenges. Design/methodology/approach The discrete element method (DEM) has been used to model the flow of cohesive materials through the transfer chute. Physical experiments have been performed to understand the most severe flow conditions. A DEM material model is also developed for replicating the worst-case material condition. After identifying the key problem areas, concept designs were proposed and simulated to assess the design improvements to increase the reliability of chute operation. Findings Flow simulations correlated well with the existing flow behavior of the iron ore fines inside the chute. The location of the problematic areas has been validated with that of the previously installed chute. Subsequently, design modifications have been proposed. This includes modification of deflector plate and change in slope and cross-section of the chute. DEM simulations and analysis were conducted after incorporating these design changes. A comparison in the average velocity of particle and force on chute wall shows a significant improvement using the proposed design. Originality/value Method to calibrate DEM material model was found to provide accurate prediction and modeling of the flow behavior of bulk material through the real transfer chute. DEM provided greater insight into the performance of the chute especially modeling cohesive materials. DEM is a valuable design tool to assist chute designers troubleshoot and verify chute designs. DEM provides a greater ability to model and assess chute wear. This technique can help in achieving a scientific understanding of the flow properties of bulk solids through transfer chute, hence eliminate challenges, ensuring reliable, uninterrupted and profitable plant operation. This paper strongly advocates the use of calibrated DEM methodology in designing bulk material handling equipment.

Pirinanın farklı nem içeriklerinde peletlenmesi işleminin peletlerin fiziksel özellikleri üzerine etkileri

Bu çalışmada, zeytinyağı üretimi sırasında yan ürün olarak ortaya çıkan pirina üç farklı nem içeriğinde (%14, %17 ve %20) peletlenmiş ve farklı nem içeriklerinin peletlerin fiziksel kalite değerleri üzerine etkisi araştırılmıştır. Nem içeriği değişkenine bağlı olarak pelet üretim koşulları ile ilgili üretim kapasitesi ve özgül enerji tüketimi değerleri belirlenmiştir. Pelet fiziksel özellikleriyle ilgili nem içeriği, parça yoğunluğu, yığın yoğunluğu, dayanıklılık direnci ve sıkıştırma direnci testleri yapılmıştır. Çalışma sonunda en yüksek üretim kapasitesi ve en düşük özgül enerji tüketimi sırasıyla 225.59 kg h-1 ve 45.13 kWh ton-1 ile %20 nem içeriğine sahip pirinada elde edilmiştir. Yüksek nem içeriğinde pelet üretiminin daha kolay gerçekleştiği ve daha az enerji gerektirdiği belirlenmiştir. Peletleme işleminde nem düzeyi artışının, parça yoğunluğu ve yığın yoğunluğu değişimine etkisi istatistiksel açıdan önemsiz bulunmuştur. Pelet dayanıklılık direnci peletleme neminin artmasıyla artış göstermiş, en yüksek dayanıklılık direnci %20 nem içeriğindeki peletleme işleminde %70 olarak hesaplanmıştır. Elde edilen peletlerin nem içeriği, yığın yoğunluğu ve dayanıklılık direnci değerleri EnPlus pelet standartlarını karşılamamaktadır. Her üç nem içeriğinde üretilen peletlerin dayanıklı yapıda olmadığı saptanmıştır. Pirina içerisinde bulunan zeytin çekirdeği parçalarının, pirinanın pelet formasyonu kazanması ve dayanıklı yapıda kalmasını engellediği sonucuna varılmıştır.

Influence of Enogen Feed corn and conventional yellow dent corn in pelleted or meal-based diets on finishing pig performance and carcass characteristics.

Genetic modification of corn has enhanced the use of different corn hybrids in animal agriculture. Enogen Feed corn, developed by Syngenta Seeds (Downers Grove, IL), has potential for use in livestock diets due to increase α-amylase enzyme in the corn thus improving starch digestibility. In addition, the pelleting process also increases starch gelatinization which increases its digestibility by the pig, increasing growth rate and improving feed efficiency. Therefore, pelleting Enogen Feed corn might prove to provide a greater response in growth performance than conventional yellow dent corn. Thus, the objective of this experiment was to determine the effects of corn source and diet form on growth performance and carcass characteristics of finishing pigs. A total of 288 pigs (53.0 ± 0.5 kg) were used with eight pigs per pen and nine pens per treatment in a 72-d study. Treatments were arranged in a 2 × 2 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and diet form (meal or pellet). For overall (d 0 to 72) performance, no interactions between corn source and diet form were observed. There was a tendency (P < 0.10) for slightly improved average daily gain (ADG) and gain:feed ratio (G:F) for pigs fed conventional yellow dent corn compared to those fed Enogen Feed corn. For feed form, pigs fed pelleted diets had increased (P < 0.001) ADG and G:F compared to pigs fed meal diets. For carcass characteristics, pigs fed pelleted diets had increased hot carcass weight compared to pigs fed meal diets (P < 0.001). In summary, feeding pelleted diets to finishing pigs increased ADG and improved feed efficiency compared to those fed meal-based diets. There were no major differences between observed corn sources or interactions between corn source and diet form on growth performance.

Processing of Agglomerates and Pellets Containing Various Amounts of Titanium Dioxide

Questions about the oxidative roasting of iron ore raw materials (agglomerates and pellets) are studied. Features of the phase structure of the iron ore raw materials containing titan and vanadium are discussed. Reducibility, durability, and the softening and melting temperatures of metallurgical iron ore raw materials are studied in vitro. The objects of the research are titaniferous ores containing different amounts of titan dioxide. The behaviors of agglomerates and pellets in a blast furnace are studied, and the influence of their physical and chemical properties on heat and mass transfer processes are researched by means of a mathematical model. The main indices of blast furnace smelting—productivity, coke consumption, composition of top gas, cast iron, and slag—are shown. It is established that the increase in titanium dioxide content in pellets, as the amount of concentrate with increased TiO2 content increases, does not cause deterioration in the quality of iron ore raw materials being prepared for blast furnace smelting. At the same time, as the hot strength of raw materials increases, the temperature at which softening begins increases and the temperature interval of softening of materials decreases.

Physical Characterization and Kinetic Analysis of the Iron Ore Pellets Produced with Marble Waste

The technical viability of the marble waste as raw material in the iron ore pelletizing sector was investigated. The effects of binary basicity (0.15 to 0.45), fixed carbon (0.5 to 1.1 wt pct), and bentonite percentages (0.5 to 0.7 wt pct) on the pellet properties were also investigated. The physical properties of the pellets were determined for drop number, tumble strength, porosity, green pellet resistance, and fired pellet resistance. The reducibility test was determined by kinetic investigation under CO flow in the temperature range of 700 °C to 1100 °C applying the Forced Stepwise Isothermal Analysis method. The results demonstrated that the marble waste has potential to be used as raw material in the iron ore pelleting process. The maximum performance was obtained with a basicity of 0.45, fixed carbon of 0.5 wt pct, and bentonite content of 0.5 wt pct. This composition reached a mechanical strength of 284.38 kgf/pellet, drop number of 3.5 drops/pellet, tumble strength of 0.56 wt pct, and green pellet resistance of 1.53 kgf/pellet. The kinetic investigation reveals that the diffusion mechanism was the best-fitted mode that displayed an activation energy of 79.4 kJ/mol between 700 °C and 800 °C and 157.2 kJ/mol in the temperature range of 850 °C to 1050 °C.

High steam-conditioning temperature during the pelleting process impairs growth performance and nutrient utilization in broiler starters fed barley-based diets, regardless of carbohydrase supplementation

The influence of supplemental carbohydrase (Carb) and conditioning temperature (CT) on growth performance, nutrient utilization and intestinal morphometry of broilers (d 1–21) fed barley-based diets was examined in a 2 × 3 factorial arrangement, evaluating 2 levels of Carb (0 and 150 g/tonne of feed) and three CT (60, 74, and 88°C). A total of 288, 1-day-old male broilers (8 birds/cage; 6 cages/treatment) were used. The activities of endo-1,4-β- glucanase, endo-1,3 (4)-β-glucanase and endo-1,4-β-xylanase in the Carb were 800 BGU/g, 700 BGU/g and 2,700 XU/g, respectively. On d 21, ileal digesta was collected for the determination of nutrient digestibility. There was no significant interaction between Carb and CT for any tested parameter. Supplemental Carb, regardless of CT, increased weight gain (WG; P < 0.05) and reduced feed per gain (F/G; P < 0.001) by 30 g/bird and 6.5 points, respectively. Increasing CT to 88°C reduced (P < 0.05) WG, but increased (P < 0.05) F/G compared to the diets conditioned at 60° and 74°C. Regardless of CT, Carb enhanced (P < 0.05) the digestibility of starch and AMEn by 1.15% and 32 kcal/kg, respectively. Compared to the diets conditioned at 60° and 74°C, CT at 88°C reduced (P < 0.05) digestibility of dry matter, nitrogen, phosphorus, gross energy, and AMEn. Birds fed diets conditioned at 88°C showed lower (P < 0.05) starch digestibility compared to those fed diets conditioned at 60°C. Conditioning at 88°C increased (P < 0.05) jejunal digesta viscosity by 10.2% compared to diets conditioned at 60° and 74°C. Overall, Carb supplementation improved WG, F/G, starch digestibility and AMEn in broilers fed barley-based diets, irrespective of CT applied. Conditioning barley-based diets at 88°C impaired the ability of birds to utilize nitrogen, starch, phosphorus and energy, and consequently deteriorated WG and F/G. The lack of significant interactions between Carb and CT indicated that negative impacts caused by high CT on bird performance and nutrient utilization occurred regardless of Carb enzyme supplementation. Supplemental Carb per se could not remedy the adverse effects of high CT.

Statistical optimization of mixed peanut shell and Khat (Catha edulis) stem carbonization process for molasses enhanced cold and low-pressure pelletization

In Ethiopia, the agricultural residues Khat (Catha edulis) stem and peanut or groundnut (Arachis hypogaea) shell are dumped in large quantities as solid waste posing significant environmental problems. This study was aimed at utilizing a mixture of these agricultural residues by combination of carbonization and cold pelleting technique. Response surface methodology (RSM) statistical experimental design was used to optimize the carbonization condition. Carbonization temperature, time, and biomass mix composition expressed as percent by weight of peanut shell (w/w %) were selected as the experimental parameters. The calorific value and charcoal yield of carbonized samples were examined as experimental responses. Based on the analysis of variance, carbonization temperature and biomass mix ratio were found significant study parameters, which affected the calorific value as well as charcoal yield. The interaction effects of the selected parameters well fitted with the second-order quadratic model equation. The optimum values of the influencing parameters were found to be at carbonization temperature of 402 °C, carbonization time of 97 min, and mix composition of 70 w/w % for maximum calorific value of 25.28 MJ/kg and charcoal yield of 41.84%. Furthermore, the mixed carbonized biomass prepared at the optimum condition was used for pellet preparation using the molasses-enhanced cold pelletization process. Results show that the density, calorific value, and mechanical strength of the pellet samples were significantly improved due to the addition of molasses as a binder.

Effect of Titanium on the Smelting Process of Chromium-Bearing Vanadium Titanomagnetite Pellets

This study discusses the smelting behaviors of chromium-bearing vanadium titanomagnetite pellets (CVTP) with TiO2 additions. The results show that the softening start temperature T10% increases from 1148°C to 1215°C, and the softening end temperature T40% increases from 1280°C to 1336°C. The melting start temperature TS increases from 1318°C to 1352°C and the dripping temperature TD decreases from 1558°C to 1505°C. The primary phases of slag are (Ti0.7V0.3)2O3, (Mg0.6Ti2.4)O5, MgSiO3, and MgTi2O5, and the equilibrium phases calculated by FactSage 7.0 verify the primary phases. The titanium-vanadium compound as an intermediate reactant is generated at the interface of pig iron and slag. The FT-IR results show the depolymerization of slag, which results in the improvement of the softening–melting behaviors.

Effects of conditioning temperature and pellet mill die speed on pellet quality and relative stabilities of phytase and xylanase.

The objective of this experiment was to determine the effect of conditioning temperature and die speed on pellet quality and enzyme stability of phytase and xylanase. Treatments were initially arranged as a 2 × 3 factorial of conditioning temperature (74 and 85 °C) and die speed (127, 190, and 254 rpm); however, when conditioning at 85 °C, it was not possible to pellet at 127 rpm. Thus, data were analyzed in two different segments using the GLIMMIX procedure of SAS. First, linear and quadratic contrasts were utilized to test the response to increasing die speed at 74 °C. Second, the data was analyzed as a 2 × 2 factorial of conditioning temperature (74 and 85 °C) and die speed (190 and 254 rpm). Treatments were arranged in a completely randomized design and replicated three times. Diets were conditioned for approximately 30 s and pelleted with a 4.8-mm-diameter × 44.5-mm-effective length die at a rate of 4.5 MT/h. Pellet durability index (PDI) was determined using the tumble box and Holmen NHP 100 methods. Samples of the unconditioned mash (M), conditioned mash (CM), and pellets (P) were collected and analyzed for phytase and xylanase concentration. Relative enzyme stabilities were expressed as CM:M, P:CM, and P:M. Stabilities expressed as P:M were used an indication of enzyme stability through the entire pelleting process. Diets conditioned at 74 °C showed no evidence of difference in phytase or xylanase P:M stability when decreasing die speed from 254 to 127 rpm. However, when conditioning diets at 74 °C, decreasing die speed increased (linear, P < 0.001) PDI. There was no conditioning temperature × die speed interaction for overall xylanase P:M stability or PDI. However, there was a conditioning temperature × die speed interaction (P < 0.01) for phytase P:M stability. When conditioning diets at 85 °C, increasing die speed decreased phytase P:M stability. However, when conditioning at 74 °C, increasing die speed did not influence phytase P:M stability. For main effects of conditioning temperature, increasing temperature improved (P < 0.001) PDI with no evidence of difference for xylanase P:M stability. For the main effects of die speed (254 vs. 190 rpm), decreasing die speed decreased (P < 0.001) the P:M xylanase stability, but there was no evidence of difference for PDI. The results of this trial indicate that die speed should be taken into consideration when evaluating enzyme stability of both phytase and xylanase as pellet mill models may be operating at different speeds. Additionally, increasing conditioning temperature will improve PDI but may result in decreased phytase stability.