| Our reserves and production of graphite resources rank first in the world.The Yunshan graphite mine is the largest graphite resources of Asia.It is located in Luobei County,Hegang City,Heilongjiang Province of China.Now 636 million tons of the graphite mines have been explored and 64.829 million tons is mineral.At present,more than 700 million tons tailings have been produced and cover nearly 136 hectares.The accumulation of graphite tailings occupy a large amount of agricultural and forest lands.The tailings exposed to the surface can easily form sand dust in windy day.The medicament remained in the tailings will directly cause serious pollution to the soil,water and atmosphere.Heavy rainfall can easily cause collapse and landslide of the tailings in the ra:iny season.Preparing the sintered brick from graphite tailings can not only reduce the accumulation of tailings and improve the environment of the mining area,but also make full use of the national resources,turn the waste into wealth and create wealth for the country,which will produce far-reaching significance to the sustainable development of our country's mining industry.In this article,sintered bricks were prepared by using the graphite tailings from Yunshan in Luobei County,Hegang City,Heilongjiang Province of China as the main raw materials and an appropriate amount of clay and slime were used,which were formed by pressing method.The influences of the ratio of raw materials,aging time,sintering temperature and constant temperature time on the properties of sintered bricks were investigated,combined with the actual situation in the industry,and the optimum process can be worked out.The results show that the graphite tailings amount is 40-45%,15%of slime,40-45%of clay,12-13%of water.Aging time is 6 days.Molding pressure is 6 MPa.Sintering temperature is 970?-1070? and the constant temperature time is 300min.Under the optimum conditions,the sintered bricks have good color consistency and higher strength,which can be well conformed to the requirements of the MU 15 in national standard GB5101-2003 and even more than MU20.The analysis of the sintering mechanism by thermogravimetric-differential thermal analysis(TG-DTA),X-ray diffraction(XRD)and scanning electron microscope(SEM)shows that the anorthite begins to crystallize at about 920?and a large number of liquid appears at about 970?-1200?.The anorthite,residual quartz and glass phase are important to the increasing of its strength.The pre-production of sintered bricks made from graphite tailings have been performed.The results show that all the properties,such as the size deviation and the appearance,can conform to the MU20 and the requirements of excellent product except the floating hoarfrost.The bulk density is 1.80 g/cm3.The water absorption of soaking for 24 hours is 14.4%;boiling for 3 hours is 15.8%;boiling for 5 hours is 16.7%.The saturation coefficient is 84%-87%.The compression strength is 22.7 MPa.There are no cracks,delamination,fading and lack of edge after the freeze-thaw cycles.The strength drops to 20.4 MPa which lose about 10%,and the mass loss is about 0.6%.There is no lime burst.However,there are a little of floating hoarfrost on the sintered bricks. |
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