Applications of our bulk material handling systems
RHEWUM offers you a wide range of bulk material handling systems: High efficiency air classifiers, optical systems, screening machines, conveying systems as well as further equipment. With ongoing research and development of our processing technology, we are constantly improving the quality of our machines.
If you have any questions on processing your materials, contact us! We will find the perfect bulk material handling system for your needs.
Gentle processing technology of high-value products We define chemical products as materials with a defined composition of various components which are not listed separately. This can be pure materials as well as mixtures. This definition is not clear-cut and may have different meaning depending on the context. Chemical products can be differentiated terminologically regarding to their different degree of purity. Chemicals with a high purity are termed fine chemicals while the term technical chemicals names materials with a lower purity. Chemical products e.g. are natural rubber, paint, cosmetics, pharmaceuticals, synthetic fertilizer, adhesives, building protective agents, cleaning agents and pyrotechnics. In processing of these substances chemical conversion is not a necessarily step but mostly physico-chemical procedures like mixing, milling, screening, extraction or emulsifying are used. The first chemicals employed in industrial processes were sulphuric acid, soda, chlorinated lime, synthetic fertilizer, plastics and colorants . These were followed by pharmaceutical agents like acetylsalicylic acid, chloral hydrate and ether. In addition to these classical screening applications, we are also capable of sieving MOFs (Metal Organic Frameworks). We recommend RHEWUM MDS screens, because of their unbeatable selectivity. The machine sieves MOFs gentle and without unnecessary product waste. MOFs are made of microporous crystalline, which consist of metallic crystal structures, known as SBUs (secondary building units), and organic molecules can be constructed (linkers) as connecting elements between the nodes. The resulting pores in the lattice structure will be filled in use with other substances. Application areas are for example the storage of gas, but also the selective separation of gases and possibly liquids. The extremely large internal surface is brought into use, which may be greater than, for example that of activated carbon and the precisely defined lattice structure. For materials of this class there are - besides the abbreviation MOF - a variety of other abbreviations such as IRMOF, HKUST, ZIF, COF, or MFU but also BAF (=University Bergakademie Freiberg. For the gentle treatment of this high grade chemical products in separation processes basically a screening process has to be chosen which processes the granulates resp. powders carefully without producing additional dust. RHEWUM: preparation processesing technology for polymers In the production of synthetic granules the polymerised pellets become screened to defined lenghts. Conventional particle size of these “On-size” pellets is between 1.6 mma nd 6.0 mm. For cooling and hardening the granues become extruded in a water quench. Afterwards the water is separated from the solids and the geranules are screenid to the defined sizes. Often the screening machines are made of stainless steel and the pellets are screened on punched plates. Sometimes the screening takes part under exclusion of oxygene. In this cases the screening machines are executed gas tight and flooded with an inert gas, e.g. nitrogen. In some cases the surface of the machines is polished. Another task in the area of polymers is the optical sorting of charges which are contaminated in terms of colour. In case of an unwanted mixing of granules with different colours they become separated by optical sorting. Polymers are polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polytetrafluorethylene (PTFE), polymethylmethaacrylate (PMMA), polyamide (PA), polyester , polycarbonate (PC) and polyethylenterephtalat (PET). In the polymerisation process these polymers are generated from monomers by polymerisation, polycondensation or polyaddition. Furthermore thermoplastics, duroplastics and elastomers are differentiated regarding to their physical characteristics. Soda Ash, Sodium Carbonate – a very fine sieving Soda Ash, Sodium Carbonate is an important additive in glass production as well as in the production of detergents and whiteners. In the glass production process soda ash is mixed with glass and melted on. The soda ash is acting as flux melting agent which reduces the melting point of the quartz powder (to approx. 850°C). When bleaching with soda the soda is dissolved after drying and screening. In the last step of neutralisation in bleaching of cotton the acid carry-over is absorbed by soda solution. In modern detergents soda is contained only indirectly as regulator for foam formation (curd soaps). Typically the screening task is to remove dust from the final soda product. The screening process mostly proceeds in a grain size range between 0.1 mm and 1.15 mm. The feed rates change between 5 t/h and 75 t/h per screening machine. Besides the product screening protection screening before packaging of the final sales products is part of the process. The possibly generated soda agglomerates are removed reliably by screening between 1 mm and 4 mm.
Chemically gypsum is calcium sulphate (CaSO 4 • 2H 2 O). In nature gypsum occurs as compact material as well as fine powder with different colours. Furthermore there are deposits containing fibrous gypsum or satin spar . Crystalline gypsum is termed selenite . Gypsum crystals are ductile and often very large. Gypsum can also be found as complex structure, the so called Gipsrose resp. Wuestenrose . Gypsum containing potassium sulphate or magnesium sulphate is termed polyhalite . The material impurified by bitumen is termed bituminous gypsum or Stinkgips . The extraction of gypsum In former times gypsum was mainly mined, in the meantime gypsum gained from flue gas desulphurisation becomes more and more. The calcinations process of the material makes use of a special characteristic of this material: in the mixing process gypsum is able to re-absorb the water of cristallisation released during calcination and to harden. During the exothermal hardening gypsum needles are formed which lead to stability. Calcinated gypsum is termed as hemhydrate , stucco or annaline . In building industry gypsum from flue gas desulphurisation is used for interior walls in form of gypsum plasterboard wall as well as filling material. Gypsum plasterboard walls ensures a proper regulation of humidity in housing spaces. Sifting gypsum In a first step gypsum is sifted directly after mining, it is humid and tends to stick together. After calcinations the material often becomes mixed together with other building materials. The particle size distribution has to be set respectively by crushing and screening. Coarse grain is unwanted since it impacts the processability negatively. Regarding to this gypsum is fine screened at high feed rates and finest separations with the demand for preferably small machines at the same time. Due to this requirements RHEWUM sifting machines are working for well known gypsum producers in Europe. We will be pleased to advise you on sifting gypsum. Please contact us by using our contact form .
The right processing of NPK fertilizer and multi-component fertilizer NPK fertilizers or composite fertilizers belong to what are defined as the mineral fertilizers consisting of the elements nitrogen (N), phosphorus (P) and potassium (K). This multi-component fertilizer is mainly produced in the manufacturing method of the drum granulation or compacting. Here the named insured components are granulated with the addition of water and other additives in the first case and compacted in the second case which means that they are cramped under high-pressure. After it the resulting granules are classified according to the screening result and crushed or compacted resp. granulated again. For industrially produced fertilizers the product has the form of granules. The particle size distribution of the multi-component fertilizers is of elementary importance: only a balanced grain distribution without dust allows modern fertilizer spreaders to reach an optimal throw which can be up to 25 m. For the user this means less effort during application of NPK composite fertilizer. The mixture of the multi-component fertilizer ensures a uniform turnout of nutrients needed by the plants. According to these advantages, NPK fertilizers are the first choice of fertilizer in the agriculture. Depending on the application traditional NPK is mixed in the ratio of 18-8-8, for example. However the composition varies adopting to the nutritional requirement of the plant or plant species. Nitrogen is of particular importance for the rapid growth of the plant – if there is a shortage the plant grows just slightly. Phosphorus is responsible for the flowering and fruiting, potassium for the resistance of the plant. The moisture which is necessarily introduced into the production is a fundamental problem in the further processing. The screening machines have to process sticky or hard-to-screen materials without clogging the screen mesh. Over the decades RHEWUM has developed special solutions for a lot of clients which have proved their value successful in practice. Our reliable screening machines of the type RHEWUM DF , RHEWUM WA and RHEWUM WAF can easily screen your NPK fertilizer without clogging the screen mesh. We offer you screening machines which achieve the highest accelerations on the mesh. Only these high frequency acceleration indemnifies the screen mesh. Your advantage: a smooth production process without repetitive cleaning work and therefore without loss of production. You don’t believe it? Please contact us, we are happy to explain your benefits in detail.
Finest sieving of dry paints in powder form Pigments, paint and colorants are chromophore substances in powder form. Pigments are insoluble in the carrier medium, colorants are soluble. The carrier medium is the substance in which the pigment is embedded, normally varnish or plastics. Colorants and pigments can be organic or inorganic, achromatic or colored. Sieving of paint and pigments Relevant for the characteristics of pigments are attributes like crystal structure , crystal modification , particle size and particle size distribution . Pigments are used in varnish , dispersion paints and printing inks , as coating pigment resp. white pigment and filler in paper production, to color plastics, in colors for artists and in crayons, for printing on textiles and special applications like cosmetics. Important inorganic pigments are haematite (red ferric oxide ), colored clay (red ochre), ochre (yellow ferric oxide) and manganese dioxide. One of the colors used since the early beginnings is white and the white pigment known for the longest time is calcium oxide (CaO) which is gained from burned lime stone . Pigments are able to adhere to aggregates. In case that these aggregates are connected at their corners or edges they are defined as agglomerates . These undesired agglomerates are separated by screening . Pigments can be used pure or with fillers e.g. as powder coating . Natural and synthetic pigments Inorganic pigments are differentiated into natural and synthetic pigments. Natural pigments are earths and minerals (earth tones and mineral white). Before use they only have to be processed mechanically, mostly drying, screening and milling. Synthetic pigments are inorganic substances like pigments giving a metallic effect, carbon black , white pigment or ferric oxide pigments . The most important pigments can be differentiated into chemical families: titanium dioxide, carbon black, bismuthinite, oxides and hydroxides, ultramarine, cadmium and chromate pigments. Oxides and hydroxides can be further classified into ferric oxide pigments, chromium oxide and mixed phase oxide pigments. Chromate pigments are further divided into chrome yellow, chrome green and Molybdate. Because of its fine particle size and its respective characteristics carbon black often is regarded as organic pigment. Due to their widespread use in industry white pigments have an exceptional position under which white minerals containing calcium carbonate are the most important. Because of its refractory index in production of varnish calcium carbonate is mainly used not as pigment but as filler. The appearance of a metal pigment is mainly determined by its particle size and the regularity of particle shape. Coarse particles give a sparkling effect while fine particles create a so called “flop” which means a smooth changeover when changing the viewing angle. Respective to this particles of a metal pigment have to be separated by size before they are embedded into the varnish. If you are planning a challenging screening of paints and pigments contact us right in time. Our PWA air jet sieve up to 400 kg per hour of carbon black at 32 µm (0.032 mm) reliably!
For the separation by particle size RHEWUM offers extremely precise screening machines that enable to produce finest metal powder (e.g. aluminum, magnesium, iron etc.) with a high quality or to process it for reutilization and separate agglomerates or dust. RHEWUM MDS: Compact screening machine for metal powders In order to achieve the desired quality of the metal powder, all impurities, undersized particles and dust need to be removed and agglomerates have to be loosened. The RHEWUM MDS sieves powdered metals from size of 40 μm very accurately and thereby reaches purities of more than 99 percent with a simultaneous yield of up to 92 percent. High-frequency unbalanced drives (>50 hertz) screen and transport the powdered metal linearly over the horizontally arranged screening surface. Due to the high frequency and low amplitude the particles undergo a high number of micro throws which are necessary for comparing the size of the particle as often as possible with the size of the screen mesh. The modular system allows to compile the rectangular sieve decks into a stack and thereby offers a large screening surface in a small place. The opportunity to arrange the sieve decks parallel to each other has the advantage that the feed quantity can be multiplied or that contamination due to tear of the screen mesh can be avoided. Wear-proof biconical bouncing balls keep the screen mesh reliably open and free during operation. RHEWUM WAF: Screening metal powder without clogging One not insubstantial challenge when sieving powdered metal is to protect the screen mesh from clogging by the extremely fine particles as the cleaning and maintenance leads to loss of the high-value metallic powder and to production downtime. The RHEWUM WAF is a combination of a directly excitated sieve and a linear vibrating conveyor that achieves better results than regular vibrating screens. The linear motion is generated by two unbalanced drives and is used to transport the material. The additional excitation of the screen mesh as well as the freely selectable cleaning sequences avoid clogging of any screening surface. The design makes it possible to adjust the screen incline of the screening machine even during operation. Loss of the valuable product and downtimes can thereby be reduced considerably. Download these information about screening metal powder as PDF here.
Salt separation with the best processing technology Table salt or cooking salt is used for food. It consists mainly of sodium chloride . In general chemical substances with ionic compounds are termed salt. Commonly sodium chloride (NaCl) resp. table salt is seen as salt. In the broader sense all compounds consisting of anions and cations like NaCl are termed as salt, e.g. calcium chloride (CaCl) or magnesium chloride (MgCl). In the extraction process of standard table salt normally 1 to 3% of other salts are remaining in rock salt as well as in sea salt. Untreated sea salt additionally contains up to 5% water. Mostly commercially traded is purified refined salt, also known as evaporated salt. For the improvement of certain characteristics as deliquescence or flowability other substances are added. For flowability these are e.g. calcium carbonate (lime), magnesium carbonate, aluminium oxide or silicates. This is done because untreated salt is hygroscopic and therefore clumps together. Salt with a high flowabilty firstly was developed in 1911 by the US-American salt producer Morton Salt . Salt processing then ... Yet the Sumerians and Babylonians used salt for the conservation of food. In German cultural area salt became affordable not before the salt layers of a thickness of hundreds of meters arising from the Zechstein sea in northern Germany were exploited. Toponyms related to salt deposits oftentimes have “salt” resp. the Middle High German term “Hall” as part of their name. Examples are Halle (Saale), Bad Reichenhall, Hallein, Hallstatt, Hall in Tirol, Schwäbisch Hall, Salzburg, Salzgitter, Salzhausen, Hansestadt Salzwedel, Bad Salzuflen, Bad Salzdetfurth, Bad Salzelmen, Bad Salzschlirf, Salzkotten and Schweizerhalle. Also the name of the holms (in German “Halligen”) in the North sea arise from the term “salt”. ... and salt processing now The mineral is mainly won underground by mining or by dissolving. By selective dissolving and concentrating as well as by evaporation the salt is separated from its impurities in salt refineries. RHEWUM screens crushed or milled rock salt as reliable as finest evaporated salt. In Germany the production of table salt makes only approx. 3% of the whole salt production. The remaining amount is used as industrial salt or de-icing salt . Starting with the development of Soda production based on the use of cooking salt by Nicolas Leblenc the step to the large-scale industrial production and use of Soda was done. Soda is used as a base material for the production of glass, textiles, detergents and cleaning agents. Therefore the areas of application for industrial salt are baking powder, glass, colorants, detergents as well as aluminium or cellulose in wad or paper. RHEWUM will be happy to advise you on the best solution for processing your salt. Contact us!