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A discrete element method (DEM), also called a distinct element method, is any of a family of numerical methods for computing the motion and effect of a large number of small particles. Though DEM is very closely related to molecular dynamics, the method is generally distinguished by its inclusion of rotational degrees-of-freedom as well as stateful contact and often complicated geometries. With advances in computing power and numerical algorithms for nearest neighbor sorting, it has become possible to numerically simulate millions of particles on a single processor. Today DEM is becoming widely accepted as an effective method of addressing engineering problems in granular and discontinuous materials, especially in granular flows, powder mechanics, and rock mechanics. DEM has been extended into the Extended Discrete Element Method taking heat transfer, chemical reaction and coupling to CFD and FEM into account.
Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust. The terms groundwater hydrology, geohydrology, and hydrogeology are often used interchangeably.
A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand or by animals, working animal, wind (windmill) or water (watermill). In modern era, they are usually powered by electricity.
Froth flotation is a process for selectively separating of hydrophobic materials from hydrophilic. This is used in mineral processing, paper recycling and waste-water treatment industries. Historically this was first used in the mining industry, where it was one of the great enabling technologies of the 20th century. It has been described as "the single most important operation used for the recovery and upgrading of sulfide ores". The development of froth flotation has improved the recovery of valuable minerals, such as copper- and lead-bearing minerals. Along with mechanized mining, it has allowed the economic recovery of valuable metals from much lower grade ore than previously.
In the field of extractive metallurgy, mineral processing, also known as ore dressing, is the process of separating commercially valuable minerals from their ores.
Reservoir simulation is an area of reservoir engineering in which computer models are used to predict the flow of fluids through porous media.
Computational science and engineering (CSE) is a relatively new discipline that deals with the development and application of computational models and simulations, often coupled with high-performance computing, to solve complex physical problems arising in engineering analysis and design as well as natural phenomena. CSE has been described as the "third mode of discovery".
A cement mill is the equipment used to grind the hard, nodular clinker from the cement kiln into the fine grey powder that is cement. Most cement is currently ground in ball mills and also vertical roller mills which are more effective than ball mills.
The particle-size distribution (PSD) of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amount, typically by mass, of particles present according to size. Significant energy is usually required to disintegrate soil, etc. particles into the PSD that is then called a grain size distribution.
Geometallurgy relates to the practice of combining geology or geostatistics with metallurgy, or, more specifically, extractive metallurgy, to create a spatially or geologically based predictive model for mineral processing plants. It is used in the hard rock mining industry for risk management and mitigation during mineral processing plant design. It is also used, to a lesser extent, for production planning in more variable ore deposits.
The CFD-DEM model, or Computational Fluid Dynamics / Discrete Element Method model, is a process used to model or simulate systems combining fluids with solids or particles. In CFD-DEM, the motion of discrete solids or particles phase is obtained by the Discrete Element Method (DEM) which applies Newton's laws of motion to every particle, while the flow of continuum fluid is described by the local averaged Navier–Stokes equations that can be solved using the traditional Computational Fluid Dynamics (CFD) approach. The interactions between the fluid phase and solids phase is modeled by use of Newton's third law.
Population balance equations (PBEs) have been introduced in several branches of modern science, mainly in Chemical Engineering, to describe the evolution of a population of particles. This includes topics like crystallization, leaching (metallurgy), liquid–liquid extraction, gas-liquid dispersions, liquid-liquid reactions, comminution, aerosol engineering, biology, polymerization, etc. Population balance equations can be said to be derived as an extension of the Smoluchowski coagulation equation which describes only the coalescence of particles. PBEs, more generally, define how populations of separate entities develop in specific properties over time. They are a set of Integro-partial differential equations which gives the mean-field behavior of a population of particles from the analysis of behavior of single particle in local conditions. Particulate systems are characterized by the birth and death of particles. For example, consider precipitation process which has the subprocesses nucleation, agglomeration, breakage, etc., that result in the increase or decrease of the number of particles of a particular radius. Population balance is nothing but a balance on the number of particles of a particular state.
Compaction simulation is the modelling of granular matter when compressed into a dense state that is achieved through the reduction of the air void. The term is also commonly used to mean compaction using a compaction simulator. This is a high performance programmable servo-controlled press for simulating production presses, typically in the pharmaceutical, catalyst, battery and magnet industries.
Comminution is the reduction of solid materials from one average particle size to a smaller average particle size, by crushing, grinding, cutting, vibrating, or other processes. In geology, it occurs naturally during faulting in the upper part of the Earth's crust. In industry, it is an important unit operation in mineral processing, ceramics, electronics, and other fields, accomplished with many types of mill. In dentistry, it is the result of mastication of food. In general medicine, it is one of the most traumatic forms of bone fracture.
The IsaMill is an energy-efficient mineral industry grinding mill that was jointly developed in the 1990s by Mount Isa Mines Limited and Netzsch Feinmahltechnik ("Netzsch"), a German manufacturer of bead mills. The IsaMill is primarily known for its ultrafine grinding applications in the mining industry, but is also being used as a more efficient means of coarse grinding. By the end of 2008, over 70% of the IsaMill’s installed capacity was for conventional regrinding or mainstream grinding applications, with target product sizes ranging from 25 to 60 µm.
The extended discrete element method (XDEM) is a numerical technique that extends the dynamics of granular material or particles as described through the classical discrete element method (DEM) by additional properties such as the thermodynamic state, stress/strain or electro-magnetic field for each particle. Contrary to a continuum mechanics concept, the XDEM aims at resolving the particulate phase with its various processes attached to the particles. While the discrete element method predicts position and orientation in space and time for each particle, the extended discrete element method additionally estimates properties such as internal temperature and/or species distribution or mechanical impact with structures.
Tumbler screening is a separation method that uses three-dimensional elliptical movement to separate very fine particles from larger ones.
Computational fluid dynamics (CFD) are used to understand complex thermal flow regimes in power plants. The thermal power plant may be divided into different subsectors and the CFD analysis applied to critical equipment/components - mainly different types of heat exchangers - which are of crucial significance for efficient and trouble free long-term operation of the plant.
Feed manufacturing refers to the process of producing animal feed from raw agricultural products. Fodder produced by manufacturing is formulated to meet specific animal nutrition requirements for different species of animals at different life stages. According to the American Feed Industry Association (AFIA), there are four basic steps:
- Receive raw ingredients: Feed mills receive raw ingredients from suppliers. Upon arrival, the ingredients are weighed, tested and analyzed for various nutrients and to ensure their quality and safety.
- Create a formula: Nutritionists work side by side with scientists to formulate nutritionally sound and balanced diets for livestock, poultry, aquaculture and pets. This is a complex process, as every species has different nutritional requirements.
- Mix ingredients: Once the formula is determined, the mill mixes the ingredients to create a finished product.
- Package and label: Manufacturers determine the best way to ship the product. If it is prepared for retail, it will be "bagged and tagged," or placed into a bag with a label that includes the product's purpose, ingredients and instructions. If the product is prepared for commercial use, it will be shipped in bulk.
Dry milling of grain is mainly utilized to manufacture feedstock into consumer and industrial based products. This process is widely associated with the development of new bio-based associated by-products. The milling process separates the grain into four distinct physical components: the germ, flour, fine grits, and coarse grits. The separated materials are then reduced into food products utilized for human and animal consumption.
References
- ↑ Prasher CL. Crushing and Grinding Process Handbook. Chichester: Wiley 1987.
- ↑ Wills BA. Mineral Processing Technology. Oxford: Pergamon Press 1992.
- ↑ Austin LG. A Review-Introduction to the Mathematical Description of Grinding as a Rate Process. Powder Technology. 1971/1972;5:1-17.
- ↑ Cundall PA, Strack ODL. A discrete numerical model for granular assemblies. Geotechnique. 1979;29:47-65