悬浮焙烧法强化从难选石煤中提取钒

提出一种难选石煤在空气气氛下悬浮焙烧-酸浸强化的提钒新技术。在焙烧温度为800℃、焙烧时间为20 min、气体流量为400 m L/min的条件下钒的浸出率从过去的20%提高到目前技术的47.14%。在焙烧过程中,石煤表面逐渐变得粗糙和不规则,颗粒比表面积增加,硅酸盐矿物的片状结构被破坏,促进了钒的释放。同时,石煤中的钒被氧化为V(Ⅴ)或V(Ⅳ)。结果表明,由于悬浮焙烧过程中钒的释放和转化,因此,其浸出率得到了提高。

A novel technology of high-voltage pulse discharge for comminution of galena ore

An innovative technology of high-voltage pulse discharge(HVPD)was proposed to investigate the comminution characteristics of galena ore.The optimal experiment parameters were determined as follows:spark gap spacing of 25 mm,pulse number of 120,and voltage of 25 k V.The mass fraction with size<0.074 mm in ground products was improved by the HVPD.Meanwhile,the relative grindability declined with the increase of the grinding time,which indicated that the superiority of HVPD was weakened.The ground products of HVPD were distributed more homogeneously than those of mechanical crushing.The liberation of breakage products was improved by 24.57%via the HVPD.Moreover,the Brunauer–Emmett–Teller(BET)specific surface area,pore volume,and average pore size were increased via the HVPD.Scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS)analyses suggested that obvious grain-boundary breakage and several stomatal traces were observed in the HVPD products.

Strengthening leaching effect of Carlin-type gold via high-voltage pulsed discharge pretreatment

A high-voltage pulsed discharge(HVPD)pretreatment was used to strengthen the leaching effect of Carlin-type gold ore containing arsenic.Optimal results of the pretreatment experiments were obtained at the following operating conditions:a spherical gap spacing of 20 mm,pulse number of 100,and voltage of 30 kV.The leaching rate of gold was increased by 15.65%via the HVPD pretreatment.The mass fraction of–0.5+0.35 mm and–0.35+0.1 mm was increased by 10.97%and 6.83%compared to the untreated samples,respectively,and the Au grade of–0.1 mm was increased by 22.84%.However,the superiority of the HVPD pretreatment would be weakened by prolonged grinding time.Scanning electron microscopy results indicated that the pretreated products presented as a melting state and then condensation,accompanying by some pore formation.More micro-cracks were generated at the interface of the ore and the original crack were expended via pulsed discharge pretreatment,with the contact area between the leaching reagent and ore increased,the leaching reaction rate enhanced and the leaching effect strengthened.

Suspension roasting process of vanadium-bearing stone coal:Characterization,kinetics and thermodynamics

The thermodynamics,kinetics,phase transformation,and microstructure evolution of vanadium-bearing stone coal during suspension roasting were systematically investigated.Thermodynamic calculations showed that the carbon in the stone coal burned and produced CO_(2) in sufficient oxygen during roasting.The mass loss of stone coal mainly occurred within the temperature range from 600 to 840℃,and the thermal decomposition reaction rate increased to the peak at approximately 700℃.Verified by the Flynn−Wall−Ozawa(FWO)and Kissinger−Akahira−Sunose(KAS)methods,the thermal decomposition reaction of stone coal was described by the Ginstling−Brounshtein equation.The apparent activation energy and pre-exponential factors were 136.09 kJ/mol and 12.40 s^(−1),respectively.The illite in stone coal lost hydroxyl groups and produced dehydrated illite at 650℃,and the structure of sericite was gradually destroyed.The surface of stone coal became rough and irregular as the temperature increased.Severe sintering occurred at the roasting temperature of 850℃.