Solidification/Stabilization of Heavy Metals by Magnesium Potassium Phosphate Cement

2013 ◽  
Vol 664 ◽  
pp. 683-689 ◽  
Author(s):  
Shu Cong Zhen ◽  
Yong Xun ◽  
Bu Quan Miao
Keyword(s):  
Heavy Metals ◽  
Unconfined Compressive Strength ◽  
Potassium Phosphate ◽  
Strength Test ◽  
Simulated Acid Rain ◽  
National Standards ◽  
Compressive Strength Test ◽  
Magnesium Potassium Phosphate Cement ◽  
Leaching Procedure ◽  
Solidified Body

Heavy metals, including Pb, Cr, Cd, Zn, Cu and Ni, were solidified/stabilized by magnesium potassium phosphate cement (MKPC). The unconfined compressive strength test shows that the strengths of the solidified bodies containing 10%-40% MKPC all exceeded 0.5 MPa, which have met the requirements of storage and landfilling. The toxicity characteristic leaching procedure (TCLP) test shows that no detectable Pb, Cr and Cd were leached from the solidified body containing 40% MKPC after being cured standardly for 28 days, and the concentrations of heavy metals leached from the solidified body containing 10% MKPC after being cured for only 7 days were still significantly lower than the limits in related Chinese National Standards. The leaching concentrations of heavy metals followed a descending order of Cu＞Zn＞Ni＞Pb＞Cd＞Cr. In the simulated acid rain eluviation test, heavy metals were eluviated in different patterns, and the sequence of releasing amounts was similar to that of leaching concentrations. The experimental results indicate that heavy metals can be satisfactorily solidified by MKPC.

Effect of Heavy Metals and Leaching Toxicity of Magnesium Potassium Phosphate Cement

2011 ◽  
Vol 117-119 ◽  
pp. 1080-1083 ◽  
Author(s):  
Bao Guo Ma ◽  
Jing Ran Wang ◽  
Xiang Guo Li
Keyword(s):  
Heavy Metals ◽  
Cement Hydration ◽  
Potassium Phosphate ◽  
National Standard ◽  
Magnesium Phosphate ◽  
Toxicity Tests ◽  
Hydration Products ◽  
Obvious Effect ◽  
Leaching Toxicity ◽  
Magnesium Potassium Phosphate Cement

Solidification / stabilization (S/S) is a popular method for treating solid wastes containing heavy metals. In recent years, it shows positive results of magnesium potassium phosphate cement as stabilizing agent. In the work, the influence of heavy metal Cu、Zn and Pb on magnesium phosphate cement and the leaching behavior of magnesium phosphate cement were studied. Two proportions of cements were employed with hard burned magnesia and potassium phosphate. The hydration products were analyzed by XRD showing that: Cu、Zn and Pb would not take on obvious effect during magnesium phosphate cement hydration process. Leaching toxicity tests showed that: Cu、Zn and Pb were immobilized within cement hydration products through physical fixation, adsorption mechanisms, and the results were far lower than that of the National Standard in China.

scholarly journals The rainfall effect onto solidification and stabilization of heavy metal-polluted sediments

2020 ◽  
Vol 7 (7) ◽  
pp. 192234
Author(s):  
Yan Sun ◽  
Daofang Zhang ◽  
Feipeng Li ◽  
Hong Tao ◽  
Moting Li ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Diffusion Coefficient ◽  
Simulated Acid Rain ◽  
Curing Process ◽  
Deterioration Rate ◽  
Before And After ◽  
Calculated Diffusion Coefficient ◽  
Leaching Procedure

Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient ( D e ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient ( D e ) for Cu was 1.28 × 10 1 cm 2 s –1 , indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients ( D i ) for Cd, Cu and Pb were 7.44 × 10 −11 , 8.18 × 10 −12 and 7.85 × 10 −12 cm 2 s –1 , respectively, indicating their relatively low mobility of heavy metal in S/S sediments.

The Research on the Application of the Steel Slag Produced by the Converters of Jigang Group Co. Ltd on Base Course

2012 ◽  
Vol 178-181 ◽  
pp. 1699-1705
Author(s):  
Fa Liang Lu ◽  
Jin Li
Keyword(s):  
Mechanical Property ◽  
Unconfined Compressive Strength ◽  
Steel Slag ◽  
Coal Ash ◽  
Strength Test ◽  
Water Stability ◽  
Compressive Strength Test ◽  
Base Course Material ◽  
Course Material ◽  
Base Course

To test and inspect the chemical compositions and mechanical properties of the steel slag produced by the converters of Jigang Group co. ltd, and study the feasibility of using the steel slag as base course material. Prepare cement stabilized steel slag specimens with different contents of cement mixed for the unconfined compressive strength test. Determine through test its strength after 7 days and 28 days and its water stability after 7 days’ soaking. Prepare in the same method of two different kinds of cement and coal ash stabilized specimens with different contents of coal ash mixed for the unconfined compressive strength test, to test its strength and water stability. The comparison on mechanical property with cement stabilized macadam indicates that the cement stabilized steel slag and cement with coal ash stabilized steel slag both have favorable mechanical property and water stability and the steel slag produced by the converters of Jigang Group co. ltd can be popularized for use as base course material.

scholarly journals Some Insights to the Reuse of Dredged Marine Soils by Admixing with Activated Steel Slag

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chee-Ming Chan ◽  
Ainun Nazhirin Abdul Jalil
Keyword(s):  
Unconfined Compressive Strength ◽  
Soil Structure ◽  
Marine Ecosystem ◽  
Steel Slag ◽  
Strength Test ◽  
Curing Time ◽  
Strength Gain ◽  
Weak Soil ◽  
Compressive Strength Test ◽  
Slag Content

Regular dredging is necessary for the development of coastal regions and the maintenance of shipping channels. The dredging process dislodges sediments from the seabed, and the removed materials, termed dredged marine soils, are generally considered a geowaste for dumping. However, disposal of the dredged soils offshores can lead to severe and irreversible impact on the marine ecosystem, while disposal on land often incurs exorbitant costs with no guarantee of zero-contamination. It is therefore desirable to reuse the material, and one option is solidification with another industrial waste, that is, steel slag. This paper describes the exploratory work of admixing dredged marine soil with activated steel slag for improvement of the mechanical properties. An optimum activation concentration of NaOH was introduced to the soil-slag mixture for uniform blending. Specimens were prepared at different mix ratios then left to cure for up to 4 weeks. The unconfined compressive strength test was conducted to monitor the changes in strength at predetermined intervals. It was found that the strength does not necessarily increase with higher steel slag content, indicating an optimum slag content required for the maximum solidification effect to take place. Also, regardless of the slag content, longer curing time produces greater strength gain. In conclusion, steel slag addition to dredged sediments can effectively strengthen the originally weak soil structure by both the “cementation” and “filler” effects, though the combined effects were not distinguished in the present study.

Study on the Strength Characteristics of Sludge Solidification

2015 ◽  
Vol 744-746 ◽  
pp. 628-631
Author(s):  
Yi Xiang Chen ◽  
Kai Xi An ◽  
Ke Xin Zhou ◽  
Chen Hao Xu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Strength Test ◽  
Experimental Results ◽  
Strength Characteristics ◽  
Curing Agent ◽  
Foundation Treatment ◽  
Compressive Strength Test ◽  
Stabilized Soil

In order to reveal the effect of type of admixture and its content on the strength of stabilized soil, this paper uses the sludge as raw soil and cement, fly ash as curing agent, and analyzes the strength characteristics of samples mixed stabilized according to certain content. Using the unconfined compressive strength test, the compressive strength of the samples is tested. The effect of curing agent type and its content on the compressive strength is investigated. From the experimental results, it can be seen that the content of cement and fly ash has much effect on the strength. The conclusions obtained can have some conference values on the foundation treatment and reuse of waste resources utilization.

Effects of Sample Preparation Methods on Tensile Strength of Red Clay

2012 ◽  
Vol 204-208 ◽  
pp. 3847-3851
Author(s):  
Zhao Tian Zeng ◽  
Hai Bo Lu ◽  
Jin Jin Zhang ◽  
Yan Lin Zhao
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Tensile Force ◽  
Strength Test ◽  
Tension Test ◽  
Red Clay ◽  
Preparation Methods ◽  
Compressive Strength Test ◽  
Sample Preparation Methods

Effects of two sample preparation methods on tensile strength of red clay are studied. The first method adopts standard layered-bumping to make sample whose layer interfaces are vertical to tensile force. The second method uses compaction apparatus to prepare big sample and the big sample is cut to prepare triaxial sample whose layer interface is parallel to tensile force. Test results indicate that the layer interfaces of soil sample have large influence on the single axle tension test, because the results of the sample prepared by 1st method have large dispersion and low strength, while the results of the sample prepared by 2nd method are just the opposite.Moreover,the layer interfaces of soil sample have little influence on the unconfined compressive strength test, and the results of the tensile test and unconfined compressive strength test of the samples prepared by 2nd method meet with the Griffith Criterion, so the samples of uniaxial tension test should be prepared by 2nd method.

Analysis of Curing Agent on the Strength of Lightweight Soil Using Recycled Sludge

2014 ◽  
Vol 936 ◽  
pp. 1382-1386
Author(s):  
Guo Cai Wang ◽  
Lin Chun Yu ◽  
Ling Sha
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Soft Soil ◽  
Strength Properties ◽  
Strength Test ◽  
Curing Agent ◽  
Test Results ◽  
Pore Characteristics ◽  
Optimum Proportion ◽  
Compressive Strength Test

In order to study the inorganic composite curing agents of lime, gypsum, fly ash on the strength properties of EPS lightweight soil using recycled sludge, the unconfined compressive strength test and scanning electron microscope test are done to investigate the strength properties of EPS lightweight soil. The effect and scope of each curing agent is investigated and determined by means of single-doped unconfined compressive strength test, and the optimum proportion of the curing agent is further determined by the method of orthogonal unconfined compressive strength test, of which the stabilized effectiveness of the lightweight soil is compared with those only using cement as curing agent. Finally, the SEM test is done to study the microstructure and pore characteristics of the lightweight soil mixed with EPS adding with or without curing agent. The test results and curing agent can be used as conference when stabilizing soft soil and treatment of discarded clay.

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