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众所周知,所有的铀矿物是氧的化合物。天然产出唯一简单氧化物是 UO_2——晶质铀矿(方铀矿和沥青铀矿)。其晶体构造相当于纯 UO_2,但是除 U~(4+)外,还包括各种数量的 U~(6+)到(U~(4+)U~(6+))O_(2-6)。据此,对铀在自然界的成因的物理化学条件进行了研究。所作的计算模型近似子天然产状。研究了 UO_2,UO_3和 U_3O_8的成因与温度(300—900°K)和压力(1—10,000大气压)的关系。在1个大气压下,自由焓的计算值表明,△G值主要是负的。因此,从理论上来说,氧化物可呈天然状态存在。同时,△G绝对值对 UO_3的形成是最有利的,但其天然状态没有见到。UO_3的形成最为有利,其理由是:在存在有剩余氧的环境下产生实验反应。所研究的氧化物形成一系列随△G值减少的化合物,就是 UO_3,U_3O_8和 UO_2。就天然状态来说,晶质铀矿(在伟晶岩中,以及在热液矿脉中)产于缺氧的情况下,因此其顺序正好与上述系列相反,只有 UO_2呈天然状态。整个情况看来,计算表明,UO_2,UO_3和 U_3O_8在压力高达10000大气压时,有可能存在。但是,增加压力对△G值有不利影响。换言之,氧化铀形成的可能性较小。根据得到的结果来看,很明显,温度对晶质铀矿的形成比压力更为重要。另一重要因素是,产生晶质铀矿环境中的化学特性。减少气压有助于 UO_2的形成,而氧化介质则抑制 UO_2的形成。将计算值与压热器中热液合成晶质铀矿的实验结果作了对比。天然晶质铀矿可能来源于伟晶岩及表生带。同时,根据 U~(6+)不同含量,晶质铀矿可以分为α,β或γ晶质铀矿或是晶质铀矿Ⅰ,Ⅱ和Ⅲ。从化学上看,这是一个 UO_2构造中的 UO_3数量变化问题,它使晶胞大小的范围(a。=5.38和a。=5.49之间产生变化。作者将计算结果和实验数据汇集起来,并将它们与在个别地方产出的晶质铀矿的整个共生次序相比较(例如在碳酸盐或硫酸盐聚集的地方),得出结论,晶质铀矿的组分和特性可作为某一种成因条件的标志。这些结果也用来预测单独矿床中晶质铀矿产地的范围。
It is well known that all uranium minerals are oxygen compounds. The only simple oxide of natural output is UO 2 - crystalline uranium (side uranium and pitch uranium). Its crystal structure is equivalent to that of pure UO_2, except for U ~ (4+), various kinds of U ~ (6+) to (U ~ (4+) U ~ (6 +)) O 2- ). Accordingly, the physico-chemical conditions of uranium in nature have been studied. The calculated model approximates the nature of the production. The relationship between the genesis of UO_2, UO_3 and U_3O_8 and temperature (300-900 ° K) and pressure (1-10,000 atmospheres) was studied. Calculations of the free enthalpy at 1 atmosphere show that the ΔG value is mainly negative. Therefore, in theory, the oxide can be in its natural state. At the same time, the absolute value of Δ G is the most favorable for the formation of UO 3, but its natural state is not seen. The formation of UO_3 is most favorable for the following reasons: experimental reactions occur in the presence of residual oxygen. The oxides studied formed a series of compounds with decreasing ΔG values, namely UO_3, U_3O_8 and UO_2. Naturally, the crystalline uranium deposits (in pegmatites and in hydrothermal veins) are produced in the absence of oxygen, so the sequence is exactly the opposite of the above series, with only UO 2 being in its natural state. It seems that the whole situation shows that UO_2, UO_3 and U_3O_8 are likely to exist at pressures as high as 10,000 atm. However, increasing the pressure has a negative effect on the ΔG value. In other words, uranium oxide is less likely to form. According to the results obtained, it is clear that the formation of crystalline uranium is more important than pressure. Another important factor is the chemical properties in a crystalline uranium environment. Reducing the pressure helps to form UO_2, whereas the oxidizing medium suppresses the formation of UO_2. The calculated results are compared with the experimental results of hydrothermal synthesis of crystalline uranium deposits in autoclave. Natural crystalline uranium may be derived from pegmatite and superficial band. Meanwhile, depending on the U ~ (6 +) content, the crystalline uranium can be divided into α, β or γ uraninite or crystalline uranium Ⅰ, Ⅱ and Ⅲ. Chemically speaking, this is a UO 3 number change problem in the UO 2 structure, which changes the range of unit cell size (a = 5.38 and a. = 5.49..) The author brings together the calculation results and the experimental data, And comparing them with the entire intergrowth order of the crystalline uraninite produced in a few places (for example where carbonate or sulfate accumulates), concludes that the composition and properties of the crystalline uranium can be used as a A hallmark of the causal conditions, these results are also used to predict the range of crystalline uranium deposits in a single deposit.