Market Stakeholder Analysis of the Practical Implementation of Carbonation Curing on Steel Slag for Urban Sustainable Governance

Carbonation curing on steel slag is one of the most promising technologies for the iron and steel industry to manage its solid waste and carbon emissions. However, the technology is still in its demonstration stage. This paper investigates the market stakeholders of carbonation curing on steel slag for construction materials for its effective application by taking China as a case study. A holistic analysis of the competition, market size, and stakeholders of carbonation curing on steel slag was carried out through a literature review, a survey, a questionnaire, and interviews. The results showed that carbonation curing on steel slag had the advantages of high quality, high efficiency, low cost, and carbon reduction compared with other technologies. Shandong province was the most suitable province for the large-scale primary application of the technology. Stakeholder involvement to establish information platforms, enhance economic incentives, and promote adequate R&D activities would promote carbonation curing of steel slag into practice. This paper provides a reference for the commercialization of carbonation curing on similar calcium- and magnesium-based solid waste materials

Carbonation Curing on Magnetically Separated Steel Slag for the Preparation of Artificial Reefs

Magnetic separation is an effective method to recover iron from steel slag. However, the ultra-fine tailings generated from steel slag become a new issue for utilization. The dry separation processes generates steel slag powder, which has hydration activity and can be used as cement filler. However, wet separation processes produce steel slag mud, which has lost its hydration activity and is no longer suitable to be used as a cement filler. This study investigates the potential of magnetically separated steel slag for carbonation curing and the potential use of the carbonated products as an artificial reef. Steel slag powder and steel slag mud were moulded, carbonation-cured and seawater-cured. Various testing methods were used to characterize the macro and micro properties of the materials. The results obtained show that carbonation and hydration collaborated during the carbonation curing process of steel slag powder, while only carbonation happened during the carbonation curing process of steel slag mud. The seawater-curing process of carbonated steel slag powder compact had three stages: C-S-H gel formation, C-S-H gel decomposition and equilibrium, which were in correspondence to the compressive strength of compact increasing, decreasing and unchanged. However, the seawater-curing process of carbonated steel slag mud compact suffered three stages: C-S-H gel decomposition, calcite transfer to vaterite and equilibrium, which made the compressive strength of compact decreased, increased and unchanged. Carbonated steel slags tailings after magnetic separation underwent their lowest compressive strength when seawater-cured for 7 days. The amount of CaO in the carbonation active minerals in the steel slag determined the carbonation consolidation ability of steel slag and durability of the carbonated steel slag compacts. This paper provides a reference for preparation of artificial reefs and marine coagulation materials by the carbonation curing of steel slag

The impact of different benefit packages of Medical Financial Assistance Scheme on health service utilization of poor population in Rural China

<p>Abstract</p> <p>Background</p> <p>Since 2003 and 2005, National Pilot Medical Financial Assistance Scheme (MFA) has been implemented in rural and urban areas of China to improve the poorest families' accessibility to health services. Local governments of the pilot areas formulated various benefit packages. Comparative evaluation research on the effect of different benefit packages is urgently needed to provide evidence for improving policy-making of MFA. This study was based on a MFA pilot project, which was one component of Health VIII Project conducted in rural China. This article aimed to compare difference in health services utilization of poor families between two benefit package project areas: H8 towns (package covering inpatient service, some designated preventive and curative health services but without out-patient service reimbursement in Health VIII Project,) and H8SP towns (package extending coverage of target population, covering out- patient services and reducing co-payment rate in Health VIII Supportive Project), and to find out major influencing factors on their services utilization.</p> <p>Methods</p> <p>A cross-sectional survey was conducted in 2004, which used stratified cluster sampling method to select poor families who have been enrolled in MFA scheme in rural areas of ChongQing. All family members of the enrolled households were interviewed. 748 and 1129 respondents from two kinds of project towns participated in the survey. Among them, 625 and 869 respondents were included (age≥15) in the analysis of this study. Two-level linear multilevel model and binomial regressions with a log link were used to assess influencing factors on different response variables measuring service utilization.</p> <p>Results</p> <p>In general, there was no statistical significance in physician visits and hospitalizations among all the respondents between the two kinds of benefit package towns. After adjusting for major confounding factors, poor families in H8SP towns had much higher frequency of MFA use (β = 1.17) and less use of hospitalization service (OR = 0.7 (H8SP/H8), 95%CI (0.5, 1.0)) among all the respondents. While calculating use of hospital services among those who needed, there was significant difference (p = 0.032) in percentage of hospitalization use between H8SP towns (46%) and H8 towns (33%). Meanwhile, the non-use but ought-to-use hospitalization ratio of H8SP (54%) was lower than that of H8 (67 %) towns. This indicated that hospitalization utilizations had improved in H8SP towns among those who needed. Awareness of MFA detailed benefit package and presence of physician diagnosed chronic disease had significant association with frequency of MFA use and hospitalizations. There was no significant difference in rate of borrowing money for illness treatment between the two project areas. Large amount of medical debt had strong association with hospitalization utilization.</p> <p>Conclusions</p> <p>The new extended benefit package implemented in pilot towns significantly increased the poor families' accessibility to MFA package in H8SP than that of H8 towns, which reduced poor families' demand of hospitalization services for their chronic diseases, and improved the poor population's utilization of out-patient services to some degree. It can encourage poor people to use more outpatient services thus reduce their hospitalization need. Presence of chronic disease and hospitalization had strong association with the presence of large amount of medical debt, which indicated that: although establishment of MFA had facilitated accessibility of poor families to this new system, and improved service utilization of poor families to some degree, but its role in reducing poor families' medical debt resulted from chronic disease and hospitalization was still very limited. Besides, the following requirements of MFA: co-payment for in-patient services, ceiling and deductibles for reimbursement, limitations on eligibility for diseases reimbursement, also served as most important obstacles for poor families' access to health care.</p> <p>Therefore, there is great need to improve MFA benefit package design in the future, including extending to cover out-patient services, raising ceiling for reimbursement, removing deductibles of MFA, reducing co-payment rate, and integrating MFA with New Rural Cooperative Medical Scheme more closely so as to provide more protection to the poor families.</p

A Study on the Fracture Control of Rock Bolts in High Ground Pressure Roadways of Deep Mines

According to the frequent fractures of rock bolts in high ground pressure roadways of deep mines, this paper analyzes the mechanism of fractures and concludes that high ground pressure and material de-fects are main reasons for the fracture of rock bolts. The basic idea of fracture control of rock bolts in high ground pressure roadways of deep mines is to increase the yield load and the limit load of rock bolt materials and reduce the actual load of rock bolts. There are four ways of controlling rock bolt fracture: increasing the rock bolt diameter, strengthening bolt materials, weakening support rigidity and the implementation of double supporting. With the roadway support of the 2302 working face of a coal mine as the project background, this paper carries out a study on the effect of two schemes, increasing the rock bolt diameter and the double supporting technique through methods of theoretical analysis, numerical simulation and so on. It determines the most reasonable diam-eter of rock bolts and the best delay distance of secondary support. Practices indicate that rock bolt fracture can be effectively controlled through the double supporting technique, which strengthens the roof and two sides through the first supporting technique and strengthens side angles through the secondary supporting technique

A Study on the Fracture Control of Rock Bolts in High Ground Pressure Roadways of Deep Mines

According to the frequent fractures of rock bolts in high ground pressure roadways of deep mines, this paper analyzes the mechanism of fractures and concludes that high ground pressure and material de-fects are main reasons for the fracture of rock bolts. The basic idea of fracture control of rock bolts in high ground pressure roadways of deep mines is to increase the yield load and the limit load of rock bolt materials and reduce the actual load of rock bolts. There are four ways of controlling rock bolt fracture: increasing the rock bolt diameter, strengthening bolt materials, weakening support rigidity and the implementation of double supporting. With the roadway support of the 2302 working face of a coal mine as the project background, this paper carries out a study on the effect of two schemes, increasing the rock bolt diameter and the double supporting technique through methods of theoretical analysis, numerical simulation and so on. It determines the most reasonable diam-eter of rock bolts and the best delay distance of secondary support. Practices indicate that rock bolt fracture can be effectively controlled through the double supporting technique, which strengthens the roof and two sides through the first supporting technique and strengthens side angles through the secondary supporting technique

The Conversion of Calcium-Containing Phases and Their Separation with NaCl in Molten Salt Chlorinated Slags at High Temperature

The titanium resources in Panxi reign, China, have a high-impurities content of Ca and Mg, which is usually processed by the molten salt chlorination process. This process allows higher Ca and Mg content in its furnace burdens. However, there is a huge amount of molten salt chlorinated slag produced by this process, consisting of complex compounds and waste NaCl/KCl salts. These slags are always stockpiled without efficient utilization, causing serious environmental pollutions. To recycle the NaCl in the slag back to the molten salt chlorination process, a novel process to deal with those molten salt chlorinated slags with phase conversion at high temperature is presented in this paper. The calcium-containing solid phase was generated when Na2SiO3 was added to the molten salt chlorinated slags at high temperature, while NaCl was kept as a liquid. Thus, liquid NaCl was easily separated from the calcium-containing solid phase, and it could be reused in the molten salt chlorination process. The conversion of calcium-containing phases and their separation of NaCl are the key parts of this work, and they have been systematically studied in this paper; thermodynamic analysis, phase transformation behavior, and calcium removal behavior have all been investigated. The calcium removal rate is 78.69% when the molar ratio of CaCl2:Na2SiO3 is 1:1.5 at 1173 K and N2 atmosphere

Orthogonal Test Design for the Optimization of Preparation of Steel Slag-Based Carbonated Building Materials with Ultramafic Tailings as Fine Aggregates

The high carbonation potential makes ultramafic tailings ideal aggregates for carbonated building materials. This paper investigates the preparation condition of ultramafic tailings and steel slag through orthogonal experiments. The results show that compressive strength has a positive exponential correlation with the CO2 uptake of the carbonated compacts. The optimized conditions include a slag-tailings ratio of 5:5, a carbonation time of 12 h, a grinding time of 0 min, and a water-solid ratio of 2.5:10, when the compressive strength of the carbonated compacts reaches 29 MPa and the CO2 uptake reaches 66.5 mg CO2/g. The effects on the compressive strength ordered from high to low impact are the slag/tailings ratio, carbonation time, grinding time of steel slag, and water–solid ratio. The effects on the CO2 uptake ordered from high to low impact are the slag–tailings ratio, water–solid ratio, carbonation time, and grinding time of steel slag. A high water–solid ratio hinders the early carbonation reactions, but promotes the long-term carbonation reaction. Steel slag is the main material being carbonated and contributes to the hardening of the compacts through carbonation curing at room temperature. Ultramafic tailings assist steel slag in hardening through minor carbonation and provide fibrous contents. The obtained results lay a solid foundation for the development of tailings-steel slag carbonated materials

Orthogonal Test Design for the Optimization of Preparation of Steel Slag-Based Carbonated Building Materials with Ultramafic Tailings as Fine Aggregates

The high carbonation potential makes ultramafic tailings ideal aggregates for carbonated building materials. This paper investigates the preparation condition of ultramafic tailings and steel slag through orthogonal experiments. The results show that compressive strength has a positive exponential correlation with the CO2 uptake of the carbonated compacts. The optimized conditions include a slag-tailings ratio of 5:5, a carbonation time of 12 h, a grinding time of 0 min, and a water-solid ratio of 2.5:10, when the compressive strength of the carbonated compacts reaches 29 MPa and the CO2 uptake reaches 66.5 mg CO2/g. The effects on the compressive strength ordered from high to low impact are the slag/tailings ratio, carbonation time, grinding time of steel slag, and water&ndash;solid ratio. The effects on the CO2 uptake ordered from high to low impact are the slag&ndash;tailings ratio, water&ndash;solid ratio, carbonation time, and grinding time of steel slag. A high water&ndash;solid ratio hinders the early carbonation reactions, but promotes the long-term carbonation reaction. Steel slag is the main material being carbonated and contributes to the hardening of the compacts through carbonation curing at room temperature. Ultramafic tailings assist steel slag in hardening through minor carbonation and provide fibrous contents. The obtained results lay a solid foundation for the development of tailings-steel slag carbonated materials