Cation and polyhedron substitution strategies: Effects on local crystal structure and on Bi3+ and Eu3+ co-doped inverse garnet phosphors’ luminescence property

Following the rapid growth of lightning technology, the development of red-emitting phosphors is effective for improving color temperature and color rendering index for w-LEDs devices. Herein, a single phased garnet phosphor with cation and polyhedron substitution modification was firstly prepared. For Mg₃Gd₂Ge₃O₁₂: Bi³⁺, Eu³⁺, the intensity has been remarkably improved by about 16% compared to the one without Bi³⁺ sensitization. The energy transfer mechanism is identified in this work. Based on cation and polyhedron substitution strategies, novel phosphors with different compositions were obtained and further modified the PL properties. With Lu³⁺ substitution, the bond lengths between Bi³⁺ ion and anion ligands are decreased and the site symmetry has been strengthened, which leads to a 21 nm blue shift when Lu³⁺ totally replaced Gd³⁺ ions. In addition, Lu³⁺ and [SiO₄] substitution strategies both effectively increased symmetric rigid structure, which leads to a significant improvement in thermal stability, indicating the samples own great potential in optical applications This work provides a new insight to synthesis red-emitting phosphors for warm white-LEDs.     

导管架平台上部组块双船拆除

为研究复杂海域环境中海洋平台双船拆除方法的安全性与可操作性,采用水动力数值计算与水池模型试验相结合的方法进行研究。将双船水动力耦合计算与水池模型试验进行对比,在相对理想海况下,结合与实际工况接近的规则波作用,进行驳船水动力性能变化与运动响应的幅值分析。在受力分析方面,对甲板耦合装置进行改良设计,对比试验数据与数值计算数据,得到受力在合理范围内的结论。研究内容为实际施工的合理性提出一定的指导性意见。     

低阶煤颗粒-气/油泡间的诱导时间研究

为表征低阶煤颗粒-气/油泡间矿化过程的差异,通过Sutherland理论下固体颗粒进入泡沫产品的总概率(E)和浮选速率常数(k)之间关系,并结合低阶煤颗粒-气/油泡的浮选速率试验,求得了低阶煤颗粒-气/油泡间的诱导时间。浮选实验研究表明,在相同的捕收剂消耗量下低阶煤-油泡浮选产率均高于低阶煤-气泡浮选产率。诱导时间测试表明,低阶煤颗粒-油泡间的诱导时间(35 ms)要明显低于低阶煤颗粒-气泡间的诱导时间(93 ms)。上述实验结果表明,油泡表面的疏水性要强于传统浮选气泡表面的疏水性。然而,进一步利用Sutherland理论中固体颗粒进入泡沫产品的总概率和浮选速率常数之间的数学关系,并结合低阶煤颗粒-气/油泡的浮选速率试验求得的低阶煤颗粒-气/油泡间的诱导时间分别为9.67和8.46 ms,其与诱导时间测试仪分别测量的诱导时间差异很大。这主要是由于在实际浮选过程中气/油泡的上升速度分别为23.26和22.68 cm/s,其远高于2015EZ型诱导时间仪测试过程中气/油泡碰撞速度(2.0 cm/s)。因此,诱导时间理论计算表明气泡-颗粒间的碰撞速度对颗粒-气泡间的诱导时间影响很大。上述研究结果表明油泡浮选效果优于传统浮选的内在原因在于低阶煤颗粒-油泡间的诱导时间小于低阶煤颗粒-气泡间的诱导时间。     

应用组合起泡剂优化黑、白钨混合浮选

针对湖南某钨选厂使用杂醇类起泡剂BK205所产生的泡沫小、性脆、泡沫层薄等不利于二次浮选的特点,采用BK205与新型醚类起泡剂CU组合使用以便实现矿石中钨矿物的高效回收。结果表明,在采用BK205与新型醚类起泡剂CU组合质量比为3∶1、先BK205后CU的加药方式下,小型闭路试验得到精矿WO3品位为30.13%,回收率为78.98%。工业试验表明,组合起泡剂不仅改善浮选泡沫,减少药剂用量,降低药剂成本,而且能获得比原起泡剂更好的工业指标,使钨矿物得到更高效的回收。     

响应面曲线法优化贵州某磷块岩浮选工艺研究

对贵州某沉积钙质磷块岩进行了浮选工艺研究。采用H₂SO₄为氟磷灰石抑制剂、BW-1为白云石捕收剂,进行了浮选单因素试验; 在此基础上进行了正交试验,并采用响应面曲线法进行了浮选条件优化。确定了最佳浮选条件为: 磨矿细度-0.074 mm粒级占60%、H₂SO₄用量13.20 kg/t和BW-1用量400 g/t。采用一段反浮选试验流程,可得到精矿品位30.94%、回收率92.45%的磷精矿。研究结果表明,磨矿细度与H₂SO₄用量的交互作用对精矿品位影响显著,H₂SO₄用量和BW-1用量的交互作用对精矿回收率影响显著。     

Cellular/dendritic transition,dendritic growth and microhardness in directionally solidified monophasic Sn-2%Sb alloy

Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb (mass fraction) alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate (V_L) and the cooling rate (T_R). High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for T_R>5.0 K/s. Cellular (l_c) and primary dendrite arm spacings (l₁) are determined along the length of the directionally-solidified casting. Experimental growth laws relating l_c and l₁ to V_L and T_R are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed.     

Effect of ultrasound on the true flotation of lignite and its entrainment behavior

In this study, the ultrasound was fixed in the pulp zone of flotation cell and its effect on the true flotation of lignite was analyzed. Flotation results indicated that the simultaneous ultrasound treatment increased the concentrate yield and decreased the concentrate ash content. Screening analysis of flotation products revealed that the ultrasound could crush coarse coal to fine coal and scanning electron microscopy (SEM) tests indicated that the ultrasound could reduce the coverage of high-ash coal fines on the coarse particle surface. Thus, the flotation recovery of coarse lignite particle was increased. In addition, the true flotation and entrainment of ?0.074 mm fine particles were studied by the sink-float test and the method of Trahar. It was found the ultrasound significantly enhanced the true flotation of fine particles and improved the overall water recovery in lignite flotation.     

钢铁企业日际煤气最优混合配比的算法研究

钢铁企业根据日际生产计划,可以确定日际生产的副产煤气总体积、各煤气消耗设备的热量需求。为进一步确定各设备消耗的混合煤气中的煤气配比,使煤气产耗平衡,提出混合煤气逆向分解方法,将各设备消耗的混合煤气中所包含的单一煤气成分体积,表示为各设备获得热量与混合煤气热值的函数,在此基础上建立日际煤气最优混合配比算法模型。该模型以各设备的混合煤气热值及热量作为决策变量,以各煤气消耗设备的热量偏差最小为目标,综合考虑各煤气设备的热值要求、自备电厂的热值、热量要求及煤气体积守恒等约束条件。采用遗传算法求解,并利用遗传算法基因初始化的范围区间控制混合煤气的热值范围。算例结果表明:建立的日际煤气最优混合配比算法模型,在优化煤气分配的同时,显著减少了约束方程及决策变量的数量,为钢铁企业日际煤气平衡调度提供了理论支撑。     

改性淀粉抑制赤铁矿反浮选石英的作用机理研究

通过矿物浮选试验、动电位测定以及吸附量测试,考察了4种淀粉抑制剂对赤铁矿和石英浮选性能的影响,并探讨了其作用机理。在碱性条件下,改性淀粉抑制剂对赤铁矿抑制效果明显,且以改性玉米淀粉效果最佳,改性磷酸酯淀粉、改性羧甲基淀粉的抑制效果次之,而普通淀粉抑制作用一般。同时4种淀粉抑制剂对主要脉石矿物石英的抑制效果均不明显。pH=10~12.5条件下,改性玉米淀粉因其羟基氧和裸露在赤铁矿表面的铁元素发生了化学键合,因而选择性抑制能力最佳。分子动力学模拟表明,改性玉米淀粉片段与赤铁矿作用更为紧密,验证了改性淀粉能更好地抑制赤铁矿。