Beneficiation of fine chromite slurry at Donskoy Mining and Beneficiation Plant JSC on concentration tables to produce hard chromite pellets

Processing industrial products and technogenic waste is an important task in the mining and metallurgical industry. In Kazakhstan, the processing of chrome ore from the Kempirsay group of deposits has produced more than 15 million tonnes of slurry tailings containing up to 30 wt% chrome oxide. The best results in the world for the processing of fine chromium raw materials are shown by Turkish enterprises with the use of the separation of slurries by size classes and beneficiation on concentration tables. The authors conducted researches for beneficiation of chrome slurry from Dubersay tailings pond (Kazakhstan) with the use of similar technological methods that enabled to obtain concentrates with chrome oxide content of 51 wt% and increasing the yield of beneficiated fine-graded chrome concentrates by 14% as compared with the existing beneficiation process. Strong chromium pellets with a crushing resistance of over 5000 N/pellet were produced from the rich chromium concentrates with the use of the ferrofluxing iron-calcium-silica binder technology by roasting the composition consisting of rich chromium concentrate, ferrous diatomite, and intermediate products and wastes of the chromium industry.

An Experimental Study of Contact Temperatures at Sealing Interface against Varying Shaft Surfaces

Increased temperatures at the sealing interface between the seal and shaft can reduce the working life of a seal through elastomer aging, swelling and increased friction. Degradation of the seal due to increased temperatures can cause pre-mature failure, wear and leakage. There is no such thing as a perfect seal; each application has requirements to cater to the needs of each system. For radial oil seals in helicopter gearboxes, the contact temperatures at the sealing interface are a critical parameter to consider. In this manuscript, investigating the factors that influence the temperatures at the contact interface shed light on the operating parameters that cause an increase in contact temperatures. Four varying shaft coatings are tested against three seal spring loads for a range of sliding velocities between 5–25 ms−1 to reproduce conditions of the gearbox. The study reveals an optimum seal spring of 12 oz, with a circumferential load of 3.34 N for lowest temperatures at the interface. Higher springs of 14 oz and lower springs of 8.5 oz both cause increased temperatures at the interface. Additionally, the need for surface coatings on the shaft is re-enforced through experimental evidence demonstrated by comparing temperatures reached between a plain stainless steel shaft and three surface coated shafts. Chrome plating shafts are undesirable due to the ‘polishing’ in effect they experience. The results of this study build on this by showing that chrome plated shafts have higher temperatures at the interface, aggravating any wear or polishing in of that surface. Contact temperatures with Tungsten carbide and Chrome oxide coatings remain within the expected temperature rise. Lastly, microscopically ‘rougher’ surfaces result in increased temperatures in contrast to surface coatings within the specified range of roughness as provided by DIN 3760/61/ISO 6194.

POTENSI PANKREAS KAMBING SEBAGAI BATING AGENT ALAMI TERHADAP KARAKTERISTIK KULIT IKAN NILA (Oreochromus niloticus) TERSAMAK(Pancreas Potential Of Goat As A Natural Bating Agent On Tilapia (Oroeochromus niloticus) Leather)

Pankreas kambing mengandung enzim proteolitik yang berpotensi sebagai bating agent dalam proses penyamakan kulit.Tujuan penelitian ini adalah mengetahui pengaruh penggunaan bating agent dari pankreas kambing terhadap karakteristik fisik kulit ikan nila tersamak dan mengetahui konsentrasi terbaik dari penggunaan bating agent pankreas kambing. Materi yang digunakan dalam penelitian ini adalah kulit ikan niladan pankreas kambing segar. Metode penelitian ini bersifat experimental laboratories menggunakan Rancangan Acak Lengkap (RAL) dengan tiga kali pengulangan dengan 4 konsentrasi bating agent yaitu (0,5%, 1%, 1,5% dan 2%) kulit ikan tersamak diuji dengankekuatan tarik, kemuluran, kekuatan sobek, kadar krom oksida, dan suhu kerut. Hasil penelitian menghasilkan bahan bating agent berpengaruh terhadap karakteristik kulit ikan tersamak (P<0,05). Konsentrasi bating agent sebesar 2% memberikan hasil yang terbaik sebagai berikut: kekuatan tarik 1300,45 N/cm², kemuluran 87,70%, kekuatan sobek 273,90 N/cm², kadar krom oksida 3,46 %, dan suhu kerut 99,75°C. Kulit ikan nila tersamak hasil penelitian semua perlakuan memenuhi persyaratan SNI 06-4586-1998 kecuali untuk parameter kemuluran tidak memenuhi syarat. Goat pancreas, containing proteolytic enzymes which the potential as a bating agent in the process of tanning the skin. The purpose of this study was to determine the effect of using bating agent from goat pancreas on the physical characteristics of tilapia skin and knowing the best concentration of using the goat pancreatic agent. The material used in this study is the skin of tilapia and fresh goat pancreas. This research method is experimental laboratories using Completely Randomized Design (CRD) with three repetitions with 4 concentrations of bating agent namely (0.5%, 1%, 1.5% and 2%) the skin of tanned fish is tested with tensile strength, elongation, tear strength, chrome oxide content, and wrinkle temperature. The results of the study resulted in bating agent material affecting the characteristics of tanned fish skin (P <0.05). Bating agent concentration of 2% gave the best results as follows: tensile strength 1300.45 N / cm², elongation 87.70%, tear strength 273.90 N / cm², chrome oxide content 3.46%, and wrinkle temperature 99, 75 ° C. The results of this study produced a total nitrogen of 2.65% of the goat pancreas which has great potential to be used as bating material. The skin of tanned tilapia from the results of this study meets the requirements of SNI 06-4586-1998 except for elongation parameters that do not meet the requirements.

Effects of Fe2O3 on Reduction Process of Cr-Containing Solid Waste Self-Reduction Briquette and Relevant Mechanism

High-temperature quench method, scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), and thermodynamic analysis were adopted to study the effects of Fe2O3 on reduction process of Cr-containing solid waste self-reduction briquette (Cr-RB). Moreover, the relevant mechanism was also studied. The results clearly showed that the addition of Fe2O3 decreased the chromium-iron ratio (Cr/(Fe + Cr)) of Cr-RB itself and promoted the reduction of chrome oxide in the Cr-containing solid wastes such as stainless steel slag and dust. A large number of Fe-C alloy droplets generated in the lower temperature could decrease the activity of reduced chromium by in situ dissolution and the reduction of Cr-oxide was accelerated. Rapid separation of metal and slag could be achieved at a relatively lower temperature, which was very beneficial to the efficient recovery of Cr. Finally, the corresponding mechanism diagram was presented.

Preparation of chrome-tanned leather shaving-based hierarchical porous carbon and its capacitance properties

A chromium oxide-carbon composite material was formed by the high-temperature carbonization of chromium-tanned leather shavings, followed by the leaching of chrome oxide and activation by KOH.

The experience of the chrome-oxide refractory materials application in the electric glassmelting furnaces

The experience of the chrome-oxide refractory materials application in the electric glass-melting furnaces for fberglass production is given in the article. The prospects are noticed of the chrome-oxide refractories using from the point of view of both the service reliability and the furnace campaign length.Ill.4. Ref. 7. Tab. 5.

Research of grain composition batch influence on alumina-zirconium silicate and alumina-chromia-zirconium silicate refractories properties

Comparative researches of grain composition batch influence with electrofusion corundum aggregate with a maximum grain size 2.0 mm or 1.0 mm on properties of alumina-zirconium silicate KTSS brand and alumina-chromia-zirconium silicate KCHTSS-30 and KCHTSS-15 brands refractories were carried out. It was established that, from batches with maximum grain size 2.0 mm and fraction content < 0.5 mm 20 % it is possible to obtain refractories with properties that approximate to the properties of refractories from batches with maximum grain size 1.0 mm and fraction content < 0.5 mm 10 %. It was shown that, for the manufacture of alumina-chromia-zirconium silicate refractories from optimal grain composition batches it is advisable to use metallurgical and pigment chromic oxide in the ratio of 2 : 1 or complete replacement of chromic oxide with mud, forming during mechanical treatment of chrome oxide refractory products. The developed compositions of batches make possible to increase efficiency of using electrofusion corundum in the manufacture of alumina-zirconium silicate and alumina-chromia-zirconium silicate refractories. Obtained results are used at making of products for glass melting furnace of industrial lining for fiberglass production from E glass.