One of the trace constituents included in cement clinker, chromium, has become prominent and highly noticed lately as a social issue both inside and outside of this country because it affects the human body negatively. The purpose of the present study was to investigate leaching properties of water-soluble hexavalent chromium by different manufacturing conditions of cement clinker. Raw materials were prepared to add different SiO2, Al2O3 and Fe2O3 sources. After the raw materials, such as limestone, sand and clay, iron ore was pulverized and mixed, and the raw meal was burnt at 1450˚C in a furnace with an oxidizing atmosphere. Leaching of soluble hexavalent chromium showed a tendency to decrease with an increasing LSF and IM. However, leaching of soluble hexavalent chromium increased with an increasing S.M. Alkali contents of iron source minerals is closely related to the leaching properties of soluble hexavalent chromium. Green sludge has the highest content of alkali added; leaching of water-soluble hexavalent chromium was mostly high. In order to reduce the water-soluble hexavalent chromium in cement, reducing the alkali content in raw materials is important.

Since it was developed by Joseph Aspdin, cement has been a common construction materials up to the present time.However, there are trace constituents in cement clinker. One of the trace constituents included in cement clinker, chromium,has become prominent and highly noticed lately as a social issue both inside and outside of this country because it affects thehuman body negatively. The aim of the present study was to investigate the concentration of water-soluble hexavalent chromiumin cement clinker by using industrial by-products. For that reason, raw materials were prepared to add different SiO2 , Al2O3,and Fe2O3 sources. After the raw materials such as the limestone, the sand and the clay, iron ore was pulverized and mixed,and the raw meal was burnt at about 1450oC in a furnace with an oxidizing atmosphere. The part in the raw materials of theclinker was substituted with slag, sludge, etc. and this was used to manufacturing cement clinker. To investigate the water-soluble hexavalent chromium content in clinker, raw meal was prepared by changing the modulus, the type, and the contentof clinker materials and tested concentrations of hexavalent chromium in the clinkers. To determine Cr+6 formation of theclinker, tests were done with raw meals adding chromium by using different industrial by-products. Consequently because thechromium was to be included in the raw materials of the clinker, production of Portland cement clinker was included with thechromium. Also, the chromium was converted into hexavalent chromium in the burning process.

This study has focused on identifying the cause of agglomeration that occurred in a domestic commercial-scale circulating fluidized bed boiler. Solid refuse fuel (SRF) was fed into the target facility to produce electricity. Agglomeration occurred in the combustor and cyclone during commercial operation. The bed material, clinkers produced in the combustor and cyclone, and boiler ash were collected, and components that are known to cause agglomeration were analyzed. Additionally, the possibility of slagging and fouling formation was predicted using components obtained by XRF analysis. The melting temperature of the bed material was decreased by complex reactions of low-boiling-point metal, alkaline metal and sulfur, and chlorine components. Then, agglomeration was generated because the bed material and ash were melted and combined. Basicity (B/A), which can lead to slagging, was estimated to be above 1.0 (reference 0.5 < B/A < 1.0). The boiler ash had a basicity of 1.83. The slag viscosity index (SVI) was estimated to be between 18.83 and 49.78 (reference 65 < SVI < 72). The boiler ash and combustor clinker had 3.30 and 4.40 total alkali (TA) values, respectively (reference 0.3 < TA < 0.4). This condition determined that slagging and fouling formation easily progressed. This result is expected to be utilized as data for preventing agglomeration formation and clinker generation.