Enhanced Mn^(2+)solidification and NH_(4)^(+)-N removal from electrolytic manganese metal residue via surfactants

Electrolytic manganese metal residue(EMMR)harmless treatment has always lacked a low-cost and quick processing technology.In this study,surfactants,namely tetradecyl trimethylammonium chloride(TTC),sodium dodecyl benzene sulfonate(SDBS),sodium lignin sulfonate(SLS),and octadecyl trimethylammonium chloride(OTC),were used in the solidification of Mn^(2+)and removal of NH_(4)^(+)-N from EMMR.The Mn^(2+)and NH_(4)^(+)-N concentrations under different reaction conditions,Mn^(2+)solidification and NH_(4)^(+)-N removal mechanisms,and leaching behavior were studied.The results revealed that the surfactants could enhance the Mn^(2+)solidification and NH_(4)^(+)-N removal from EMMR,and the order of enhancement was as follows:TTC>SDBS>OTC>SLS.The NH_(4)^(+)-N and Mn^(2+)concentrations were 12.3 and 0.05 mg·L^(-1)with the use of 60.0 mg·kg^(-1)TTC under optimum conditions(solid–liquid ratio of 1.5:1,EMMR to BRM mass ratio of 100:8,temperature of 20℃,and reaction duration of 12 h),which met the integrated wastewater discharge standard(GB8978-1996).Mn^(2+)was mainly solidified as Mn(OH)_(2),MnOOH and MnSiO_(3),and NH_(4)^(+)-N in EMMR was mostly removed in the form of ammonia.The results of this study could provide a new idea for cost-effective EMMR harmless treatment.

Comprehensive recovery of lead, zinc, and iron from hazardous jarosite residues using direct reduction followed by magnetic separation

Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rates of lead and zinc and the metallization rate of iron were investigated. The results show that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, and the iron metallization rate was 91.97% under the optimal reduction roasting conditions of a coal dosage of 25.0 wt% and reduction roasting at 1250°C for 60 min. The magnetic concentrate with an iron content of 90.59 wt% and an iron recovery rate of 50.87% was obtained under the optimum conditions in which 96.56% of the reduction product particles were smaller than 37 μm and the magnetic field strength was 24 k A/m. Therefore, the results of this study demonstrate that recovering valuable metals such as lead, zinc, and iron from jarosite residues is feasible using the developed approach.

Continued Diagnostic Difficulties in Preoperatively Differentiating Lipiodized Oil and Residual Metallic Material: A Case Report

Retained foreign objects in the abdomen and pelvis are serious clinical problems yet the imaging required can present difficulties. Prolonged retention of lipiodized oil used for hysterosalpingography over years is very rare. However, lipiodized oil had previously been misdiagnosed as residual metallic material. We are reporting a case in which the latest computed tomography (CT) equipment seemed inadequate for obtaining a clear pre-operative diagnosis. Here, we describe the case of a 33-year-old Japanese female whose pelvis had contained retained lipiodized oil that had been suspected as residual metallic material. The preoperative diagnosis was very difficult and included three-dimensional computed tomography (3D-CT) of unclear results despite expectations of resolution. By laparoscopic surgery, we removed a cyst of approximately 2 cm containing a yellowish oily fluid. Postoperatively, we demonstrated that the fluid was lipiodized oil. A postoperative experiment to attempt distinguishing lipiodized oil from metal through gemstone spectral CT imaging did not offer clarity either. Distinguishing between retained lipiodized oil and metallic material in the abdominal cavity may still present unexpected difficulties even with the latest medical equipments.

EFFECT OF TENSILE STRESS AND RESIDUAL STRESS ON THE SPONTANEOUS STRAY FIELD SIGNALS FROM THE SURFACE OF 0.45%C STEEL

In order to explore the quantitative method of metal magnetic memory testing（MMMT） and clarify the relationship between Hp（y）, the normal component of spontaneous stray field, and applied stress or residual stress, the static tensile tests of 0.45%C steel sheet specimens are carried out on a servo hydraulic MTS810 machine. Hp（y） values are measured during the test process by an EMS-2003 metal magnetic memory diagnostic apparatus and a non-magnetic electric control displacement instrument. Residual stresses of some points on the surface of a specimen are measured by a Stress Tech X-Stress 3000 X-ray diffraction instrument. The results show that the same variation rules of Hp（y） value versus applied tensile stress are presented under the different conditions of load-on and load-off. However, the same rule does not exist between the Hp（y） value and residual stress. The variation of Hp（y） value reflects the history of applied tensile stress.

Serrated plastic flow behavior and microstructure in a Zr-based bulk metallic glass processed by surface mechanical attrition treatment

The serrated plastic flow,microstructure and residual stress of a Zr_（55）Cu_（30）Ni_5Al_（10） bulk metallic glass（BMG）undergone surface mechanical attrition treatment（SMAT）have been investigated by a combination of compression tests with scanning electron microscopy（SEM）,high resolution transmission electron microscopy（HRTEM）and the incremental hole-drilling strain-gage method.It is found that SMAT leads to various microstructural modifications and residual stress distribution in the surface layers of the Zrbased BMG due to the mechanically-induced nanocrystallization and generation of shear bands.As a result,the BMG alloy exhibits a remarkable work-hardening like behavior and significant increase of plastic strain from less than 1%to 15%,and its plastic deformation dynamics yields a power-law distribution of shear avalanches.Based upon the analysis of the experimental results,it is indicated that this can be connected to the SMAT-induced microstructural modifications and the resulting residual compressive stress in the Zr-based BMG.

Phytotoxicity and groundwater impacts of leaching from thermal treatment residues in roadways

The use of coal fly ash（CFA）, municipal solid waste incinerator bottom ash（MSWIBA） and flue gas desulfurization residue（FGDR） in road construction has become very common owing to its economical advantages. However, these residues may contain toxic constituents that pose an environmental risk if they leach out and flow through the soil, surface water and groundwater.Therefore, it is necessary to assess the ecotoxicity and groundwater impact of these residues before decisions can be made regarding their utilization for road construction. In this study,the physico-chemical characteristics, leaching and phytotoxicity of these residues were investigated. Specifically, multivariate analyses were used to evaluate the contributions of the leaching constituents of the CFA, MSWIBA and FGDR leachates to the germination index of wheat seeds. B, Ba, Cr, Cu, Fe and Pb were found to be more toxic to the wheat seeds than the other heavy metals. Furthermore, the leached concentrations of the constituents from the CFA, MSWIBA and FGDR were below the regulatory threshold limits of the Chinese identification standard for hazardous wastes. Analyses conducted using a numerical groundwater model（Wisc LEACH） indicated that the predicted field concentrations of metals from the CFA, MSWIBA and FGDR increased with time up to about 30 years at the point of compliance, then decreased with time and distance. Overall, this study demonstrated that the risks resulting from MSWIBA, CFA and FGDR leaching could be assessed before its utilization for road construction, providing crucial information for the adoption of these alternative materials.

Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies

Impact of waste fuels（virgin/waste wood, mixed biofuel（peat, bark, wood chips） industrial,household, mixed waste fuel） and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr,As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature.Total concentration in ashes decreased in order of Zn 〉 Cu 〉 Pb 〉 Cr 〉 Sb 〉 As 〉 Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers（especially for biofuel incineration）. It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions.Concentration levels in ash and ash matrix properties（association of elements on ash particles）are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in 〉50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.