A new low-cost method of reclaiming mixed foundry waste sand based on wet-thermal composite reclamation

A lot of mixed clay-resin waste sand from large-scale iron foundries is discharged every day; so mixed waste sand reclamation in low cost and high quality has a great realistic significance. In the study to investigate the possibility of reusing two types of waste foundry sands, resin bonded sand and clay bonded sand which came from a Chinese casting factory, a new low-cost reclamation method of the mixed foundry waste sand based on the wet-thermal composite reclamation was proposed. The waste resin bonded sand was first reclaimed by a thermal method and the waste clay bonded sand was reclaimed by a wet method. Then, hot thermal reclaimed sand and the dehydrated wet reclaimed sand were mixed in certain proportions so that the hot thermal reclaimed sand dried the wet reclaimed sand leaving some water. The thermal reclamation efficiency of the waste resin bonded sand was researched at different heat levels. The optimized wet reclamation process of the waste clay bonded sand was achieved by investigating the effects of wet reclamation times, sand-water ratio and pH value on the reclaimed sand characteristics. The composite reclamation cost also was calculated. The research results showed that the properties of the mixed reclaimed sand can satisfy the application requirements of foundries; in which the temperature of the thermal reclamation waste resin bonded sand needs to be about 800 oC, the number of cycles of wet reclamation waste clay bonded sand should reach four to five, the optimal sand-water ratio of wet reclamation is around 1:1.5, and the pH value should be adjusted by adding acid. The mass ratio of hot thermal reclaimed sand to dehydrated wet reclaimed sand is about 1:2.5, and the composite reclaimed sand cost is around 100 yuan RMB per ton.

Research,application and development of inorganic binder for casting process

Inorganic binder used in casting process has the advantages of low odor,labor-friendly conditions,and relatively low cost,which is one of the main development directions for casting molding materials in the future.However,compared to organic binders(such as resin binders),inorganic binders exhibit lower bonding strength and are more sensitive to environmental humidity.This sensitivity poses challenges,particularly in the reclamation of used sand,thus limiting their broader application.In this paper,the research and application status of inorganic binders(mainly silicate inorganic binders)and their curing methods are summarized.In addition,the research and application of phosphate inorganic binders and 3D printing inorganic binders that are being developed are introduced.Meanwhile,a detailed comparative analysis is conducted on the challenging issue of“reclamation for used sand”in the application of inorganic binders.Finally,the development direction of inorganic binders is clarified.

Irrigation of Romaine Lettuce (Lactuca sativa)Using Wastewater Treated byNon-Conventional Technologies

The aim of this study was to assess the capacity for reuse of wastewater treated in stabilisation ponds and subsequently reclaimed by means of different filtration systems at pilot scale. An analysis of filtered water showed turbidity values of below 5 NTU, a total suspended solids (TSS) content of 7 mg/l, and Escherichia coli values of up to 1.6 log CFU/100 ml. These results fall within the parameters stipulated in RD 1620/2007 Spanish Water Reuse Regulations governing the reuse of reclaimed wastewater for agricultural purposes. The water reclaimed by means of filtration systems was used to irrigate Romainelettuce (Lactuca sativa longifolia), comparing growth with that of the same variety irrigated with water from the supply network. The results showed a mean difference in lettuce growth of up to 300% in favour of the crop irrigated with reclaimed water.

Growth and competition among understory plants varies with reclamation soil and fertilization

Introduction:Following oil sands mining in Alberta,Canada,the main land management goal is to establish a functioning boreal forest ecosystem,including the understory plant community.One of the challenges with restoring the understory is the presence of non-native species that compete with desirable native species for resources.In a greenhouse experiment,we studied the growth of two native understory species(Galium boreale and Vicia americana)and a non-native invasive species(Matricaria perforata)grown with either intra-or interspecific neighbors across three common land reclamation soils and a nitrogen fertilizer treatment.Results:When grown by itself,V.americana aboveground biomass did not differ among soil or fertilizer treatments,likely due to its ability to fix nitrogen.Growth of M.perforata was directly related to soil nitrogen,and it had the greatest increase in biomass with fertilization.Growth and biomass of G.boreale was less than the other species,and it had the highest mortality in the nitrogen-poor soil.When grown together,the proportional biomass of M.perforata and V.americana varied with soil treatment such that M.perforata was dominant in the high-nitrogen forest floormineral mix treatment while V.americana was dominant in the low-nitrogen peat-mineral mix.Conclusions:Operationally,care should be taken when applying fertilizer to reclamation areas,as it may have an unwanted positive effect on growth for undesirable non-native plants at the expense of native species.In terms of seed mixtures,V.americana may be a good option for low inorganic nitrogen resource soils and G.boreale for high nitrogen resource soils.